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Perpendicular magnetic anisotropy at transition metal/oxide interfaces and applications

B. Dieny* and M. Chshiev†

B. Dieny* and M. Chshiev†

  • Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble, France, CEA, INAC-SPINTEC, F-38000 Grenoble, France, and CNRS, SPINTEC, F-38000 Grenoble, France

  • *bernard.dieny@cea.fr
  • †mair.chshiev@cea.fr
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Rev. Mod. Phys. 89, 025008 – Published 28 June, 2017

DOI: https://doi.org/10.1103/RevModPhys.89.025008

Abstract

Spin electronics is a rapidly expanding field stimulated by a strong synergy between breakthrough basic research discoveries and industrial applications in the fields of magnetic recording, magnetic field sensors, nonvolatile memories [magnetic random access memories (MRAM) and especially spin-transfer-torque MRAM (STT-MRAM)]. In addition to the discovery of several physical phenomena (giant magnetoresistance, tunnel magnetoresistance, spin-transfer torque, spin-orbit torque, spin Hall effect, spin Seebeck effect, etc.), outstanding progress has been made on the growth and nanopatterning of magnetic multilayered films and nanostructures in which these phenomena are observed. Magnetic anisotropy is usually observed in materials that have large spin-orbit interactions. However, in 2002 perpendicular magnetic anisotropy (PMA) was discovered to exist at magnetic metal/oxide interfaces [for instance Co(Fe)/alumina]. Surprisingly, this PMA is observed in systems where spin-orbit interactions are quite weak, but its amplitude is remarkably large—comparable to that measured at Co/Pt interfaces, a reference for large interfacial anisotropy (anisotropy∼1.4  erg/cm2=1.4  mJ/m2). Actually, this PMA was found to be very common at magnetic metal/oxide interfaces since it has been observed with a large variety of amorphous or crystalline oxides, including AlOx, MgO, TaOx, HfOx, etc. This PMA is thought to be the result of electronic hybridization between the oxygen and the magnetic transition metal orbit across the interface, a hypothesis supported by ab initio calculations. Interest in this phenomenon was sparked in 2010 when it was demonstrated that the PMA at magnetic transition metal/oxide interfaces could be used to build out-of-plane magnetized magnetic tunnel junctions for STT-MRAM cells. In these systems, the PMA at the CoFeB/MgO interface can be used to simultaneously obtain good memory retention, thanks to the large PMA amplitude, and a low write current, thanks to a relatively weak Gilbert damping. These two requirements for memories tend to be difficult to reconcile since they rely on the same spin-orbit coupling. PMA-based approaches have now become ubiquitous in the designs for perpendicular STT-MRAM, and major microelectronics companies are actively working on their development with the first goal of addressing embedded FLASH and static random access memory-type of applications. Scalability of STT-MRAM devices based on this interfacial PMA is expected to soon exceed the 20-nm nodes. Several very active new fields of research also rely on interfacial PMA at magnetic metal/oxide interfaces, including spin-orbit torques associated with Rashba or spin Hall effects, record high speed domain wall propagation in buffer/magnetic metal/oxide-based magnetic wires, and voltage-based control of anisotropy. This review deals with PMA at magnetic metal/oxide interfaces from its discovery, by examining the diversity of systems in which it has been observed and the physicochemical methods through which the key roles played by the electronic hybridization at the metal/oxide interface were elucidated. The physical origins of the phenomenon are also covered and how these are supported by ab initio calculations is dealt with. Finally, some examples of applications of this interfacial PMA in STT-MRAM are listed along with the various emerging research topics taking advantage of this PMA.

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References (314)

  1. Abate, E., and M. Adsente, 1965, “Tight-binding calculation of 3d bands of Fe with and without spin-orbit coupling,” Phys. Rev. 140, A1303.
  2. Akinaga, H., and H. Shima, 2010, “Resistive Random Access Memory (ReRAM) based on metal oxides,” Proc. IEEE 98, 2237–2251.
  3. Aliev, F. G., J. P. Cascales, A. Hallal, M. Chshiev, and S. Andrieu, 2014, “Band-edge noise spectroscopy of a magnetic tunnel junction,” Phys. Rev. Lett. 112, 216801.
  4. Andersson, C., B. Sanyal, O. Eriksson, L. Nordström, O. Karis, D. Arvanitis, T. Konishi, E. Holub-Krappe, and J. Hunter Dunn, 2007, “Influence of Ligand States on the Relationship between Orbital Moment and Magnetocrystalline Anisotropy,” Phys. Rev. Lett. 99, 177207.
  5. Avci, C. O., K. Garello, I. M. Miron, G. Gaudin, S. Auffret, O. Boulle, and P. Gambardella, 2012, “Magnetization switching of an MgO/Co/Pt layer by in-plane current injection,” Appl. Phys. Lett. 100, 212404.
  6. Bae, J. S., K. H. Shin, T. D. Lee, and H. M. Lee, 2002, “Study of the effect of natural oxidation and thermal annealing on microstructures of AlOx in the magnetic tunnel junction by high-resolution transmission electron microscopy,” Appl. Phys. Lett. 80, 1168–1170.
  7. Bai, Z., L. Shen, G. Han, and Y. P. Feng, 2012, “Data storage: Review of Heusler compounds,” SPIN 02, 1230006.
  8. Baibich, M., J.-M. Broto, A. Fert, F. Nguyen Van Dau, F. Petroff, P. Etienne, G. Creuzet, A. Friederich, and J. Chazelas, 1988, “Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices,” Phys. Rev. Lett. 61, 2472.
  9. Ballhausen, C. J., 1962, Introduction to Ligand Field Theory (McGraw-Hill, New York).
  10. Bandiera, S., et al., 2011, “Spin transfer torque switching assisted by thermally induced anisotropy reorientation in perpendicular magnetic tunnel junctions,” Appl. Phys. Lett. 99, 202507.
  11. Barati, E., M. Cinal, D. M. Edwards, and A. Umerski, 2013, “Calculation of Gilbert damping in ferromagnetic films,” EPJ Web Conf. 40, 18003.
  12. Barnes, S. E., J. Ieda, and S. Maekawa, 2014, “Rashba Spin-Orbit Anisotropy and the Electric Field Control of Magnetism,” Sci. Rep. 4, 4105.
  13. Barsukov, I., Y. Fu, A. M. Gonçalves, M. Spasova, M. Farle, R. E. Arias, and I. N. Krivorotov, 2014, “Field-dependent perpendicular magnetic anisotropy in CoFeB thin films,” Appl. Phys. Lett. 105, 152403.
  14. Bauer, G. E., W. E. Saitoh, and B. J. Van Wees, 2012, “Spin-caloritronics,” Nat. Mater. 11, 391–399.
  15. Bauer, U., M. Przybylski, J. Kirschner, and G. S. D. Beach, 2012, “Magnetoelectric charge trap memory,” Nano Lett. 12, 1437.
  16. Bauer, U., L. Yao, A. J. Tan, P. Agrawal, S. Emori, H.-L. Tuller, S. van Dijken, and G. S. D. Beach, 2015, “Magneto-ionic control of interfacial magnetism,” Nat. Mater. 14, 174–181.
  17. Bedau, D., H. Liu, J. Bouzaglou, A. D. Kent, J. Z. Sun, J. A. Katine, E. E. Fullerton, and S. Mangin, 2010, “Ultrafast spin transfer switching in spin valve nanopillars with perpendicular anisotropy,” Appl. Phys. Lett. 96, 022514.
  18. Beleggia, M., M. De Graef, Y. T. Millev, D. A. Goode, and G. Rowlands, 2005, “Demagnetization factors for elliptic cylinders,” J. Phys. D 38, 3333.
  19. Berger, L., 1996, “Emission of spin waves by a magnetic multilayer traversed by a current,” Phys. Rev. B 54, 4828–4830.
  20. Berger, L., 1999, “Generation of dc voltages by a magnetic multilayer undergoing ferromagnetic resonance,” Phys. Rev. B 59, 11465–11470.
  21. Bernas, H., J.-P. Attané, K. H. Heinig, D. Halley, D. Ravelosona, A. Marty, P. Auric, C. Chappert, and Y. Samson, 2003, “Ordering intermetallic alloys by ion irradiation: A way to tailor magnetic media,” Phys. Rev. Lett. 91, 077203.
  22. Bethe, H. A., 1929, “Splitting of Terms in Crystals,” Ann. Phys. (Berlin) 395, 133–206.
  23. Binasch, G., P. Grünberg, F. Saurenbach, and W. Zinn, 1989, “Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange,” Phys. Rev. B 39, 4828–4830.
  24. Bloch, F., and G. Gentile, 1931, “Zur Anisotropie der Magnetisierung ferromagnetischer Einkristalle,” Z. Phys. 70, 395.
  25. Blonski, P., and J. Hafner, 2009, “Density-functional theory of the magnetic anisotropy of nanostructures: An assessment of different approximations,” J. Phys. Condens. Matter 21, 426001.
  26. Bogdanov, A. N., and U. K. Röszligler, 2001, “Chiral symmetry breaking in magnetic thin films and multilayers,” Phys. Rev. Lett. 87, 037203.
  27. Bonell, F., S. Murakami, Y. Shiota, T. Nozaki, T. Shinjo, and Y. Suzuki, 2011, “Large change in perpendicular magnetic anisotropy induced by an electric field in FePd ultrathin films,” Appl. Phys. Lett. 98, 232510.
  28. Bonell, F., et al., 2012, “Spin-polarized electron tunneling in bcc FeCo/MgO/FeCo(001) magnetic tunnel junctions,” Phys. Rev. Lett. 108, 176602.
  29. Bonell, F., Y. T. Takahashi, D. D. Lam, S. Yoshida, Y. Shiota, S. Miwa, T. Nakamura, and Y. Suzuki, 2013, “Reversible change in the oxidation state and magnetic circular dichroism of Fe driven by an electric field at the FeCo/MgO interface,” Appl. Phys. Lett. 102, 152401.
  30. Bose, T., R. Cuadrado, R. F. L. Evans, R. V. Chepulskii, D. Apalkov, and R. W. Chantrell, 2016, “First-principles study of the FeMgO(001) interface: magnetic anisotropy,” J. Phys. Condens. Matter 28, 156003.
  31. Boulle, O., S. Rohart, L. D. Buda-Prejbeanu, E. Jué, I. M. Miron, S. Pizzini, J. Vogel, G. Gaudin, and A. Thiaville, 2013, “Domain wall tilting in the presence of the Dzyaloshinskii-Moriya interaction in out-of-plane magnetized magnetic nanotracks,” Phys. Rev. Lett. 111, 217203.
  32. Boulle, O., et al., 2016, “Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures,” Nat. Nanotechnol. 11, 449.
  33. Brooks, H., “Ferromagnetic Anisotropy and the Itinerant Electron Model,” 1940, Phys. Rev. 58, 909.
  34. Bruno, P., 1989, “Tight-binding approach to the orbital magnetic moment and magnetocrystalline anisotropy of transition-metal monolayers,” Phys. Rev. B 39, 865–868(R).
  35. Bruno, P., 1993, “Physical origins and theoretical models of magnetic anisotropy,” in Magnetismus von Festkörpern und Grenzflächen, IFF Ferienkurs, edited by P. H. Dederichs, P. Grünberg, and W. Zinns (Forschungszentrum Jülich), pp. 24.1–24.8.
  36. Bruno, P., and J.-P. Renard, 1989, “Magnetic surface anisotropy of transition metal ultrathin films,” Appl. Phys. A 49, 499–506.
  37. Butler, W. H., 2008, “Tunneling magnetoresistance from a symmetry filtering effect,” Sci. Technol. Adv. Mater. 9, 014106.
  38. Butler, W. H., X. G. Zhang, S. Vutukuri, M. Chshiev, and T. C. Schulthess, 2005, “Theory of tunneling magnetoresistance for epitaxial systems,” IEEE Trans. Magn. 41, 2645–2648.
  39. Butler, W. H., X.-G. Zhang, T. C. Schulthess, and J. M. MacLaren, 2001, “Spin-dependent tunneling conductance of FeMgO|Fe sandwiches,” Phys. Rev. B 63, 054416.
  40. Carcia, P. F., A. D. Meinhaldt, and A. Suna, 1985, “Perpendicular magnetic anisotropy in Pd/Co thin film layered structures,” Appl. Phys. Lett. 47, 178–180.
  41. Carson, G. A., M. H. Nassir, and M. A. Langell, 1996, “Epitaxial growth of Co3O4 on CoO(100),” J. Vac. Sci. Technol. A 14, 1637–1642.
  42. Chappert, C., and P. Bruno, 1988, “Magnetic anisotropy in metallic ultrathin films and related experiments on cobalt films,” J. Appl. Phys. 64, 5736–5741.
  43. Chappert, C., A. Fert, and F. Van Dau, 2007, “The emergence of spin electronics in data storage,” Nat. Mater. 6, 813–823.
  44. Chen, X., C. Feng, Z. L. Wu, F. Yang, Y. Liu, S. Jiang, M. H. Li, and G. H. Yu, 2014, “Interfacial oxygen migration and its effect on the magnetic anisotropy in Pt/Co/MgO/Pt films,” Appl. Phys. Lett. 104, 052413.
  45. Chien, C. L., S. H. Liou, B. K. Ha, and K. M. Unruh, 1985, “Rapidly quenched FexTa100–x alloys,” J. Appl. Phys. 57, 3539–3541.
  46. Choi, H. S., et al., 2014, “Spin nano-oscillator-based wireless communication,” Sci. Rep. 4, 5486.
  47. Chung, S.-W., et al., 2016, “4 Gbit density STT-MRAM using perpendicular MTJ realized with compact cell structure,” Electron Devices Meeting (IEDM), 2016 IEEE International, p. 27.1.1.
  48. Cros, V., J. Grollier, M. Munoz Sanchez, A. Fert, and F. Nguyen Van Dau, 2014, “Spintronic device with control by domain wall displacement induced by a current of spin-polarized carriers,” Patent US 7969762 B2.
  49. Cubukcu, M.O. Boulle, M. Drouard, K. Garello, C. O. Avci, I. M. Miron, J. Langer, B. Ocker, P. Gambardella, and G. Gaudin, 2014, “Spin-orbit torque magnetization switching of a three-terminal perpendicular magnetic tunnel junction,” Appl. Phys. Lett. 104, 042406.
  50. Cuchet, L., B. Rodmacq, S. Auffret, R. C. Sousa, and B. Dieny, 2014, “Influence of magnetic electrodes thicknesses on the transport properties of magnetic tunnel junctions with perpendicular anisotropy,” Appl. Phys. Lett. 105, 052408.
  51. Cuchet, L., B. Rodmacq, S. Auffret, R. C. Sousa, I. L. Prejbeanu, and B. Dieny, 2015, “Perpendicular magnetic tunnel junctions with double barrier and single or synthetic antiferromagnetic storage layer,” J. Appl. Phys. 117, 233901.
  52. Da Costa, V., A. Iovan, K. Ounadjela, W. Allen, J. F. Gregg, and B. Dieny, 2002, “Spin-polarized electronic reflections at metal-oxide interfaces,” J. Magn. Magn. Mater. 240, 140–142.
  53. Daalderop, G. H. O., P. J. Kelly, and F. J. A. den Broeder, 1992, “Prediction and confirmation of perpendicular magnetic anisotropy in Co/Ni multilayers,” Phys. Rev. Lett. 68, 682–685.
  54. Daalderop, G. H. O., P. J. Kelly, and M. F. H. Schuurmans, 1990, “First-principles calculation of the magnetic anisotropy energy of (Co)n/(X)m multilayers,” Phys. Rev. B 42, 7270–7272(R).
  55. Daalderop, G. H. O., P. J. Kelly, and M. F. H. Schuurmans, 1994a, “Magnetic anisotropy of a free-standing Co monolayer,” Phys. Rev. B 50, 9989–10003.
  56. Daalderop, G. H. O., P. J. Kelly, and M. F. H. Schuurmans, 1994b, “Magnetic anisotropy from first principles,” in Ultrathin Magnetic Structures I, edited by J. A. C. Bland and B. Heinrich (Springer, Berlin), pp. 40–64.
  57. Dahmane, Y., C. Arm, S. Auffret, U. Ebels, B. Rodmacq, and B. Dieny, 2009, “Oscillatory behavior of perpendicular magnetic anisotropy in Pt/Co/Al(Ox) films as a function of Al thickness,” Appl. Phys. Lett. 95, 222514.
  58. Den Broeder, F. J. A., H. C. Donkersllot, H. J. G. Draaisma, and W. J. M. de Jonge, 1987, “Magnetic properties and structure of Pd/Co and Pd/Fe multilayers,” J. Appl. Phys. 61, 4317–4319.
  59. Den Broeder, F. J. A., W. Hoving, and P. J. H. Bloemen, 1991, “Perpendicular magnetic anisotropy,” J. Magn. Magn. Mater. 93, 562–570.
  60. Devolder, T., I. Barisic, S. Eimer, K. Garcia, J.-P. Adam, B. Ockert, and D. Ravelosona, 2013, “Irradiation-induced tailoring of the magnetism of CoFeB/MgO ultrathin films,” J. Appl. Phys. 113, 203912.
  61. Devolder, T., P.-H. Ducrot, J.-P. Adam, I. Barisic, N. Vernier, J. V. Kim, B. Ockert, and D. Ravelosona, 2013, “Damping of CoxFe80−xB20 ultrathin films with perpendicular magnetic anisotropy,” Appl. Phys. Lett. 102, 022407.
  62. Dieny, B., and O. Redon, 2001, “Magnetic tunnel junction, magnetic device, memory and writing and reading methods using said devices,” Patent Application US 6,950,335B2.
  63. Dieny, B., S. Sankar, M. McCartney, D. Smith, P. Bayle-Guillemaud, and A. Berkowitz, 1998, “Spin-polarized tunneling in discontinuous metal/insulator multilayers,” J. Magn. Magn. Mater. 185, 283–292.
  64. Dieny, B., V. S. Speriosu, S. S. P. Parkin, B. A. Gurney, D. R. Wilhoit, and D. Mauri, 1991, “Giant magnetoresistance in soft ferromagnetic multilayers,” Phys. Rev. B 43, 1297–1300.
  65. Dieny, B., et al., 2010, “Spin-transfer effect and its use in spintronic components,” Int. J. Nanotechnology 7, 591–614.
  66. Ding, M., and Poon, S. J., 2012, “Perpendicular magnetization of Co20Fe50Ge30 films induced by MgO interface,” Appl. Phys. Lett. 101, 122408.
  67. Du, C., H. Wang, F. Yang, and P. C. Hammel, 2014, “Systematic variation of spin-orbit coupling with d-orbital filling: Large inverse spin Hall effect in 3d transition metals,” Phys. Rev. B 90, 140407(R).
  68. Duan, C.-G., J. P. Velev, R. F. Sabirianov, Z. Zhu, J. Chu, S. S. Jaswal, and E. Y. Tsymbal, 2008, “Surface magnetoelectric effect in ferromagnetic metal films,” Phys. Rev. Lett. 101, 137201.
  69. Dussaux, A., et al., 2010, “Large microwave generation from current-driven magnetic vortex oscillators in magnetic tunnel junctions,” Nat. Commun. 1, 8.
  70. Dynna, M., J.-L. Vassent, A. Marty, and B. Gilles, 1996, “Low energy electron diffraction investigation of the surface deformation induced by misfit dislocations in thin MgO films grown on Fe(001),” J. Appl. Phys. 80, 2650–2657.
  71. Dzialoshinskii, I. E., 1957, “Thermodynamic theory of weak ferromagnetism in antiferromagnetic substances,” Zh. Eksp. Teor. Fiz. 32, 1547–1562; JETP 5, 1259–1272 (1957) [http://www.jetp.ac.ru/cgi-bin/e/index/e/5/6/p1259?a=list].
  72. Egelhoff, W. F., P. J. Chen, C. J. Powell, M. D. Stiles, R. D. McMichael, J. H. Judy, K. Takano, A. Berkowitz, and J. M. Daughton, 1997, “Specular electron scattering in giant magnetoresistance spin valves,” IEEE Trans. Magn. 33, 3580–3582.
  73. Emori, S., U. Bauer, S.-M. Ahn, E. Martinez, and G. S. D. Beach, 2013, “Current-driven dynamics of chiral ferromagnetic domain walls,” Nat. Mater. 12, 611–616.
  74. Emori, S., D. C. Bono, and G. S. D. Beach, 2012, “Interfacial current-induced torques in Pt/Co/GdOx,” Appl. Phys. Lett. 101, 042405.
  75. Emori, S., T. Nan, A. M. Belkessam, X. Wang, A. D. Matyushov, C. J. Babroski, Y. Gao, H. Lin, and N. X. Sun, 2016, “Interfacial spin-orbit torque without bulk spin-orbit coupling,” Phys. Rev. B 93, 180402(R).
  76. Endo, M., S. Kanai, S. Ikeda, F. Matsukura, and H. Ohno, 2010, “Electric-field effects on thickness dependent magnetic anisotropy of sputtered MgO/Co 40 Fe 40 B 20 / Ta structures,” Appl. Phys. Lett. 96, 212503.
  77. Fabian, J., and S. Das Sarma, 1999, “Spin relaxation of conduction electrons,” J. Vac. Sci. Technol. B 17, 1708–1715.
  78. Farle, M., 1998, “Ferromagnetic resonance of ultrathin metallic layers,” Rep. Prog. Phys. 61, 755.
  79. Faure-Vincent, J., et al., 2003, “High tunnel magnetoresistance in epitaxial Fe/MgO/Fe tunnel juncitons,” Appl. Phys. Lett. 82, 4507.
  80. Fert, A., V. Cros, and J. Sampaio, 2013, “Skyrmions on the track,” Nat. Nanotechnol. 8, 152–156.
  81. Fuchs, G. D., N. C. Emley, I. N. Krivorotov, P. M. Braganca, E. M. Ryan, S. I. Kiselev, J. C. Sankey, D. C. Ralph, and R. A. Buhrman, 2004, “Spin-transfer effects in nanoscale magnetic tunnel junctions,” Appl. Phys. Lett. 85, 1205–1207.
  82. Gabor, M. S., T. Petrisor, Jr., C. Tiusan, and T. Petrisor, 2013, “Perpendicular magnetic anisotropy in Ta/Co2FeAl/MgO multilayers,” J. Appl. Phys. 114, 063905.
  83. Gambardella, P., and I. M. Miron, 2011, “Current-induced spin-orbit torques,” Phil. Trans. R. Soc. A 369, 3175–3197.
  84. Garello, K., I. M. Miron, C. O. Avci, F. Freimuth, Y. Mokrousov, S. Blügel, S. Auffret, O. Boulle, G. Gaudin, and P. Gambardella, 2013, “Symmetry and magnitude of spin-orbit torques in ferromagnetic heterostructures,” Nat. Nanotechnol. 8, 587–593.
  85. Gaudin, G., I. M. Miron, P. Gambardella, and A. Schuhl, 2010, “A writable magnetic memory element,” Patent application US 2012020152A1; “A writable magnetic element,” Patent applications US 2012018822A1, US 2012098077A1.
  86. Gay, J. G., and R. Richter, 1986, “Spin anisotropy of ferromagnetic films,” Phys. Rev. Lett. 56, 2728–2731.
  87. Gehanno, V., A. Marty, B. Gilles, and Y. Samson, 1997, “Magnetic domains in epitaxial ordered FePd(001) thin films with perpendicular magnetic anisotropy,” Phys. Rev. B 55, 12552–12555.
  88. Giannozzi, P., et al., 2009, “QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials,” J. Phys. Condens. Matter 21, 395502.
  89. Gottwald, M., et al., 2012, “Co/Ni(111) superlattices studied by microscopy, X-ray absorption, and ab initio calculations,” Phys. Rev. B 86, 014425.
  90. Grimbolt, J., J.-P. Bonnelle, and J.-P. Beaufils, 1976, “ESCA study on cobalt and molybdenum deposited on alumina—quantitative analysis of recovery and states of specific cation absorption,” J. Electron Spectrosc. Relat. Phenom. 8, 437–447.
  91. Guoa, V. W., B. Lu, X. Wu, G. Ju, B. Valcu, and D. Weller, 2006, “A survey of anisotropy measurement techniques and study of thickness effect on interfacial and volume anisotropies in Co/Pt multilayer media,” J. Appl. Phys. 99, 08E918.
  92. Ha, S.-S., N.-H. Kim, S. Lee, C.-Y. You, Y. Shiota, T. Maruyama, T. Nozaki, and Y. Suzuki, 2010, “Voltage induced magnetic anisotropy change in ultrathin Fe80Co20/MgO junctions with Brillouin light scattering,” Appl. Phys. Lett. 96, 142512.
  93. Hallal, A., B. Dieny, and M. Chshiev, 2014, “Impurity-induced enhancement of perpendicular magnetic anisotropy in Fe/MgO tunnel junctions,” Phys. Rev. B 90, 064422.
  94. Hallal, A., H. X. Yang, B. Dieny, and M. Chshiev, 2013, “Anatomy of perpendicular magnetic anisotropy in Fe/MgO magnetic tunnel junctions: First-principles insight,” Phys. Rev. B 88, 184423.
  95. Heinonen, O. G., and D. V. Dimitrov, 2010, “Switching-current reduction in perpendicular-anisotropy spin torque magnetic tunnel junctions,” J. Appl. Phys. 108, 014305.
  96. Heinze, S., K. von Bergmann, M. Menzel, J. Brede, A. Kubetzka, R. Wiesendanger, G. Bihlmayer, and S. Blugel, 2011, “Spontaneous atomic-scale magnetic skyrmion lattice in two dimensions,” Nat. Phys. 7, 713–718.
  97. Hrabec, A., N. A. Porter, A. Wells, M. J. Benitez, G. Burnell, S. McVitie, D. McGrouther, T. A. Moore, and C. H. Marrows, 2014, “Measuring and tailoring the Dzyaloshinskii-Moriya interaction in perpendicularly magnetized thin films,” Phys. Rev. B 90, 020402(R).
  98. Hu, G., et al., 2015, “STT-MRAM with double magnetic tunnel junctions,” Electron Devices Meeting (IEDM), 2015 IEEE International, p. 26.3.1.
  99. Huai, Y., 2008, “Spin transfer torque MRAM (STT-MRAM): Challenges and prospects,” A.A.P.P.S. Bull. 18, 33–40.
  100. Huai, Y., F. Albert, P. Nguyen, M. Pakala, and T. Valet, 2004, “Observation of spin-transfer switching in deep submicron-sized and low-resistance magnetic tunnel junctions,” Appl. Phys. Lett. 84, 3118–3120.
  101. Huang, R. T., F. R. Chen, J. J. Kai, I. F. Tsu, S. Mao, and W. Kai, 2001, “Diffusion behavior of the spin valve structure,” J. Appl. Phys. 89, 7625–7627.
  102. Ibrahim, F., A. Hallal, B. Dieny, and M. Chshiev, 2016a, “Giant variation of the perpendicular magnetic anisotropy at Fe/MgO interfaces by oxygen migration: a first-principles study,” arXiv:1610.08859
  103. Ibrahim, F., H. X. Yang, A. Hallal, B. Dieny, and M. Chshiev, 2016b, “Anatomy of electric field control of perpendicular magnetic anisotropy at Fe/MgO interfaces,” Phys. Rev. B 93, 014429.
  104. Iihama, S., S. Mizukami, H. Naganuma, M. Oogane, Y. Ando, and T. Miyazaki, 2014, “Gilbert damping constants of Ta/CoFeB/MgO(Ta) thin films measured by optical detection of precessional magnetization dynamics,” Phys. Rev. B 89, 174416.
  105. Ikeda, S., J. Hayakawa, Y. Ashizawa, Y. M. Lee, K. Miura, H. Hasegawa, M. Tsunoda, F. Matsukura, and H. Ohno, 2008, “Tunnel magnetoresistance of 604% at 300 K by suppression of Ta diffusion in CoFeB/MgO/CoFeB pseudo-spin-valves annealed at high temperature,” Appl. Phys. Lett. 93, 082508.
  106. Ikeda, S., J. Hayakawa, Y. M. Lee, R. Sasaki, T. Meguro, F. Matsukura, and H. Ohno, 2005, “Dependence of tunnel magnetoresistance in MgO based magnetic tunnel junctions on Ar pressure during MgO sputtering,” Jpn. J. Appl. Phys. 44, L1442–L1445.
  107. Ikeda, S., K. Miura, H. Yamamoto, K. Mizunuma, H. D. Gan, M. Endo, S. Kanai, J. Hayakawa, F. Matsukura, and H. Ohno, 2010, “A perpendicular-anisotropy CoFeB–MgO magnetic tunnel junction,” Nat. Mater. 9, 721–724.
  108. ITRS, 2010, http://www.itrs.net/Links/2010ITRS/2010Update/ToPost/ERD_ERM_2010FINALReportMemory Assessment_ITRS.pdf.
  109. Iwasaki, J., M. Mochizuki, and N. Nagaosa, 2013, “Current-induced skyrmion dynamics in constricted geometries,” Nat. Nanotechnol. 8, 742–747.
  110. Jan, G., Y.-J. Wang, T. Moriyama, Y.-J. Lee, M. Lin, T. Zhong, R.-Y. Tong, T. Torng, and P.-K. Wang, 2012, “High spin torque efficiency of magnetic tunnel junctions with MgO/CoFeB/MgO free layer,” Appl. Phys. Express 5, 093008.
  111. Jansen, H. J. F., “Magnetic anisotropy in density-functional theory,” 1988, Phys. Rev. B 38, 8022.
  112. Je, S. G., D. H. Kim, S. C. Yoo, B. C. Min, K. J. Lee, and S. B. Choe, 2013, “Asymmetric magnetic domain-wall motion by the Dzyaloshinskii-Moriya interaction,” Phys. Rev. B 88, 214401.
  113. Jiang, W., et al., 2015, “Blowing magnetic skyrmion bubbles,” Science 349, 283–286.
  114. Johnson, M. T., P. J. H. Bloemen, F. J. A. den Broeder, and J. J. de Vries, 1996, “Magnetic anisotropy in metallic multilayers,” Rep. Prog. Phys. 59, 1409–1458.
  115. Johnson, M. T., R. Jungblut, P. J. Kelly, and F. J. A. den Broeder, 1995, “Perpendicular magnetic anisotropy of multilayers: Recent insights,” J. Magn. Magn. Mater. 148, 118–124.
  116. Jones, W., and N. H. March, “Theoretical Solid State Physics: Perfect lattices in equilibrium,” 1973, John Wiley and Sons Ltd, New York.
  117. Kambersky, V., 1976, “On ferromagnetic resonance damping in metals,” Czech. J. Phys. B 26, 1366–1383.
  118. Kanai, S., M. Tsujikawa, Y. Miura, M. Shirai, F. Matsukura, and H. Ohno, 2014, “Magnetic anisotropy in Ta/CoFeB/MgO investigated by x-ray magnetic circular dichroism and first-principles calculation,” Appl. Phys. Lett. 105, 222409.
  119. Karthik, S. V., Y. K. Takahashi, T. Ohkubo, K. Hono, H. D. Gan, S. Ikeda, and H. Ohno, 2012, “Transmission electron microscopy study on the effect of various capping layers on CoFeB/MgO/CoFeB pseudo spin valves annealed at different temperatures,” J. Appl. Phys. 111, 083922.
  120. Katine, J. A., F. J. Albert, R. A. Buhrman, E. B. Myers, and D. C. Ralph, 2000, “Current-driven magnetization reversal and spin-wave excitations in Co/Cu/Co pillars,” Phys. Rev. Lett. 84, 3149–3152.
  121. Kato, T., Y. Matsumoto, S. Kashima, S. Okamoto, N. Kituchi, S. Iwata, O. Kitakami, and S. Tsunashima, 2012, “Perpendicular anisotropy and Gilbert damping in sputtered Co/Pd multilayers,” IEEE Trans. Magn. 48, 3288–3291.
  122. Kawahara, T., 2011, “Scalable spin-transfer torque RAM technology for normally-off computing,” IEEE Design & Test of Computers 28, 52–63.
  123. Kent, A. D., B. Ozyilmaz, and E. del Barco, 2004, “Spin-transfer-induced precessional magnetization reversal,” Appl. Phys. Lett. 84, 3897–3899.
  124. Khomski, D., 2014, “Transition metal compounds” (Cambridge University Press, Cambridge, England).
  125. Khoo, K. H., G. Wu, M. H. Jhon, M. Tran, F. Ernult, K. Eason, H. J. Choi, and C. K. Gan, 2013, “First-principles study of perpendicular magnetic anisotropy in CoFe/MgO and CoFe/Mg3B2O6 interfaces,” Phys. Rev. B 87, 174403.
  126. Khvalkovskiy, A. V., et al., 2013, “Basic principles of STT-MRAM cell operation in memory arrays,” J. Phys. D 46, 074001.
  127. Kim, J., J. Sinha, M. Hayashi, M. Yamanouchi, S. Fukami, T. Suzuki, S. Mitani, and H. Ohno, 2013, “Layer thickness dependence of the current-induced effective field vector in Ta/CoFeB/MgO,” Nat. Mater. 12, 240–245.
  128. Kim, W., et al., 2011, “Extended scalability of perpendicular STT-MRAM toward sub-20 nm MTJ node,” Electron Devices Meeting (IEDM), 2011 IEEE International, 24.1.1–24.1.4.
  129. Kishi, T., et al., 2008, “Lower-current and fast switching of a perpendicular TMR for high speed and high density spin-transfer-torque MRAM,” Electron Devices Meeting (IEDM), 2008 IEEE International, p. 1.
  130. Kita, K., D. W. Abraham, M. J. Gajek, and D. C. Worledge, 2012, “Electric-field control of magnetic anisotropy of Co0.6Fe0.2B0.2/oxide stacks using reduced voltage,” J. Appl. Phys. 112, 033919.
  131. Koch, R., 1997, “Intrinsic stress of epitaxial thin films and surface layers,” in Growth and Properties of Ultrathin Epitaxial Layers, edited by O. A. King and D. P. Woodruff (Elsevier Science, New York), Chap. 12, pp. 448–489.
  132. Koch, R. H., J. A. Katine, and J. Z. Sun, 2004, “Time-resolved reversal of spin transfer switching in a nanomagnet,” Phys. Rev. Lett. 92, 088302.
  133. Koo, J. W., S. Mitani, T. T. Sasaki, H. Sukegawa, Z. C. Wen, T. Ohkubo, T. Niizeki, K. Inomata, and K. Hono, 2013, “Large perpendicular magnetic anisotropy at Fe/MgO interface,” Appl. Phys. Lett. 103, 192401.
  134. Kozina, X., S. Ouardi, B. Balke, G. Stryganyuk, G. H. Fecher, C. Felser, S. Ikeda, H. Ohno, and E. Ikenaga, 2010, “A non-destructive analysis of the B diffusion in Ta/CoFeB/MgO/CoFeB/Ta magnetic tunnel junctions by hard X-ray photoemission,” Appl. Phys. Lett. 96, 072105.
  135. Koziol-Rachwal, A., T. Slezak, P. Kuzwik, M. Urbaniak, F. Stobiescki, L. D. Yao, S. van Dijken, and J. Koerchi, 2014, “Tunable magnetic properties of monoatomic metal-oxide Fe/MgO multilayers,” Phys. Rev. B 90, 045428.
  136. Koziol-Rachwal, A., et al., 2013, “Room-temperature perpendicular magnetic anisotropy of MgO/Fe/MgO ultrathin films,” J. Appl. Phys. 114, 224307.
  137. Kubota, H., S. Ishibashi, T. Saruya, T. Nozaki, A. Fukushima, K. Yakushiji, K. Ando, Y. Suzuki, and S. Yuasa, 2012, “Enhancement of perpendicular magnetic anisotropy in FeB free layers using a thin MgO cap layer,” J. Appl. Phys. 111, 07C723.
  138. Kyuno, K., R. Yamamoto, and S. Asano, 1992, “Theoretical study on the magnetocrystalline anisotropy of X/Co (X = Pd, Pt, Cu, Ag, Au) multilayers,” J. Phys. Soc. Jpn. 61, 2099–2113.
  139. Lambert, C. H., A. Rajanikanth, T. Hauet, S. Mangin, and E. E. Fullerton, 2013, “Quantifying perpendicular magnetic anisotropy at the Fe/MgO(001) interface,” Appl. Phys. Lett. 102, 122410.
  140. Lee, D. S., H. T. Chang, C. W. Cheng, and G. Chern, 2014, “Perpendicular magnetic anisotropy in MgO/CoFeB/Nb and a comparison of the cap layer effect,” IEEE Trans. Magn. 50, 3201904.
  141. Lee, H., Y. H. A. Wang, C. K. A. Mewes, W. H. Butler, T. Mewes, S. Maat, B. York, M. J. Carey, and J. R. Childress, 2009, “Magnetization relaxation and structure of CoFeGe alloys,” Appl. Phys. Lett. 95, 082502.
  142. Lee, K., J. J. Sapan, S. H. Kang, and E. E. Fullerton, 2011, “Perpendicular magnetization of CoFeB on single crystal MgO,” J. Appl. Phys. 109, 123910.
  143. Lee, K. J., O. Redon, and B. Dieny, 2005, “Analytical investigation of spin-transfer dynamics using a perpendicular-to-plane polarizer,” Appl. Phys. Lett. 86, 022505.
  144. Lee, O. J., V. S. Pribiag, P. M. Braganca, P. G. Gowtham, D. C. Ralph, and R. A. Buhrman, 2009, “Ultrafast switching of a nanomagnet by a combined out-of-plane and in-plane polarized spin-current pulse,” Appl. Phys. Lett. 95, 012506.
  145. Lee, S.-C., K.-S. Kim, S.-H. Lee, U.-H. Pi, K. Kim, Y. Jang, and Y. I. Chung, 2013, “Effect of Fe-O distance on magnetocrystalline anisotropy energy at the Fe/MgO(001) interface,” J. Appl. Phys. 113, 023914.
  146. Lee, Y. M., J. Hayakawa, S. Ikeda, F. Matsukura, and H. Ohno, 2006, “Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer,” Appl. Phys. Lett. 89, 042506.
  147. Lessard, A., T. H. Moos, and W. Hübner, 1997, “Magnetocrystalline anisotropy energy of transition-metal thin films: A nonperturbative theory,” Phys. Rev. B 56, 2594.
  148. Li, D., C. Barreteau, and A. Smogunov, 2016, “Magnetocrystalline anisotropy of Fe and Co slabs and clusters on SrTiO3 by first-principles,” Phys. Rev. B 93, 144405.
  149. Li, D., A. Smogunov, C. Barreteau, F. Ducastelle, and D. Spanjaard, 2013, “Magnetocrystalline anisotropy energy of Fe(001) and Fe(110) slabs and nanoclusters: A detailed local analysis within a tight-binding model,” Phys. Rev. B 88, 214413.
  150. Li, Z., and S. Zhang, 2004, “Thermally assisted magnetization reversal in the presence of a spin-transfer torque,” Phys. Rev. B 69, 134416.
  151. Liang, S.-H., et al., 2014, “Large and robust electrical spin injection into GaAs at zero magnetic field using an ultrathin CoFeB/MgO injector,” 2014, Phys. Rev. B 90, 085310.
  152. Lide, D. R., 2000, Handbook of Chemistry and Physics (CRC, Boca Raton), 81st ed., Sec. 5.
  153. Lin, W., N. Vernier, G. Agnus, K. Garcia, B. Ocker, W. Zhao, E. E. Fullerton, and D. Ravelosona, 2016, “Universal domain wall dynamics under electric field in Ta/CoFeB/MgO devices with perpendicular anisotropy,” Nat. Commun. 7, 13532.
  154. Liu, L., O. J. Lee, T. J. Gudmundsen, D. C. Ralph, and R. A. Buhrman, 2012, “Current-induced switching of perpendicularly magnetized magnetic layers using spin torque from the spin Hall effect,” Phys. Rev. Lett. 109, 096602.
  155. Liu, L., C. F. Pai, Y. Li, H. W. Tseng, D. C. Ralph, and R. A. Buhrman, 2012, “Spin-torque switching with the giant spin Hall effect of tantalum,” Science 336, 555–558.
  156. Liu, T., J. W. Cai, and L. Sun, 2012, “Large enhanced perpendicular magnetic anisotropy in CoFeB/MgO system with the typical Ta buffer replaced by an Hf layer,” AIP Adv. 2, 032151.
  157. Liu, T., Y. Zhang, J. W. Cai, and H. Y. Pan, 2014, “Thermally robust Mo/CoFeB/MgO trilayers with strong perpendicular magnetic anisotrop,” Sci. Rep. 4, 5895.
  158. Liu, X., W. Zhang, M. J. Carter, and G. Xiao, 2011, “Ferromagnetic resonance and damping properties of CoFeB thin films as free layers in MgO-based magnetic tunnel junctions,” J. Appl. Phys. 110, 033910.
  159. Lu, Y., et al., 2012, “Spin-orbit coupling effect by minority interface resonance states in single-crystal magnetic tunnel junctions,” Phys. Rev. B 86, 184420.
  160. Ma, Q. L., S. Lihama, T. Kubota, X. M. Zhang, S. Mizukami, Y. Ando, and T. Miyazaki, 2012, “Effect of Mg interlayer on perpendicular magnetic anisotropy of CoFeB films in MgO/Mg/CoFeB/Ta structure,” Appl. Phys. Lett. 101, 122414.
  161. Manchon, A., and S. Zhang, 2008, “Theory of nonequilibrium intrinsic spin torque in a single nanomagnet,” Phys. Rev. B 78, 212405.
  162. Manchon, A., and S. Zhang, 2009, “Theory of spin torque due to spin-orbit coupling,” Phys. Rev. B 79, 094422.
  163. Manchon, A., et al., 2008, “Analysis of anisotropy crossover due to oxygen in Pt/Co/MOx trilayers,” J. Appl. Phys. 104, 043914.
  164. Maruyama, T., et al., 2009, “Large voltage-induced magnetic anisotropy change in a few atomic layers of iron,” Nat. Nanotechnol. 4, 158–161.
  165. Mathon, J., and A. Umerski, 2001, “Theory of tunneling magnetoresistance of an epitaxial Fe/MgO/Fe(001) junction,” Phys. Rev. B 63, 220403.
  166. Mattheiss, L. F., 1972, “Energy Bands for KNiF3, SrTiO3, KMoO3, and KTaO3,” Phys. Rev. B 6, 4718.
  167. Meiklejohn, W. H., 1962, “Exchange Anisotropy—A Review,” J. Appl. Phys. 33, 1328.
  168. Meyerheim, H. L., R. Popescu, J. Kirschner, N. Jedrecy, M. Sauvage-Simkin, B. Heinrich, and R. Pinchaux, 2001, “Geometrical and compositional structure at metal-oxide interfaces: MgO on Fe(001),” Phys. Rev. Lett. 87, 076102.
  169. Min, T., et al., 2010, “A study of write margin of spin torque transfer magnetic random access memory technology,” IEEE Trans. Magn. 46, 2322–2327.
  170. Miron, I. M., K. Garello, G. Gaudin, P.-J. Zermatten, M. V. Costache, S. Auffret, S. Bandiera, B. Rodmacq, A. Schuhl, and P. Gambardella, 2011, “Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection,” Nature (London) 476, 189–193.
  171. Miron, I. M., G. Gaudin, S. Auffret, B. Rodmacq, A. Schuhl, S. Pizzini, J. Vogel, and P. Gambardella, 2010, “Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer,” Nat. Mater. 9, 230–234.
  172. Miron, I. M., P.-J. Zermatten, G. Gaudin, S. Auffret, B. Rodmacq, and A. Schuhl, 2009, “Domain wall spin torque meter,” Phys. Rev. Lett. 102, 137202.
  173. Miron, I. M., et al., 2011, “Fast current-induced domain-wall motion controlled by the Rashba effect,” Nat. Mater. 10, 419–423.
  174. Miwa, S., et al., 2014, “Highly sensitive nanoscale spin-torque diode,” Nat. Mater. 13, 50–56.
  175. Miyakawa, N., D. C. Worledge, and K. Kita, 2013, “Impact of Ta diffusion on the perpendicular magnetic anisotropy of Ta/CoFeB/MgO,” IEEE Magn. Lett. 4, 1000104.
  176. Miyazaki, T., and N. Tezuka, 1995, “Giant magnetic tunneling effect in Fe/Al2O3/Fe junction,” J. Magn. Magn. Mater. 139, L231–L234.
  177. Monso, S., B. Rodmacq, S. Auffret, G. Casali, F. Fettar, B. Gilles, B. Dieny, and P. Boyer, 2002, “Crossover from in-plane to perpendicular anisotropy in Pt/CoFe/AlOx as a function of the Al degree of oxidation: A very accurate control of the oxidation of tunnel barrier,” Appl. Phys. Lett. 80, 4157–4159.
  178. Moodera, J. S., L. R. Kinder, T. M. Wong, and R. Meservey, 1995, “Large magnetoresistance at room temperature in ferromagnetic thin film tunnel junctions,” Phys. Rev. Lett. 74, 3273–3276.
  179. Moriya, T., 1960, “Anisotropic superexchange interaction and weak ferromagnetism,” Phys. Rev. 120, 91–98.
  180. Mouillon, A., et al., 2016 (to be published).
  181. Mühlbauer, S., et al., 2009, “Skyrmion lattice in a chiral magnet,” Science 323, 915–919.
  182. Mukherjee, S. S., D. Mac Mahon, F. Bai, C. L. Lee, and S. K. Kurinec, 2009, “Study of boron diffusion in MgO in CoFeB-MgO film stacks using parallel electron energy loss spectroscopy,” Appl. Phys. Lett. 94, 082110.
  183. Nakamura, K., T. Akiyama, T. Ito, M. Weinert, and A. J. Freeman, 2010, “Role of an interfacial FeO layer in the electric-field-driven switching of magnetocrystalline anisotropy at the Fe/MgO interface,” Phys. Rev. B 81, 220409(R).
  184. Nakamura, K., R. Shimabukuro, Y. Fujiwara, T. Akiyama, T. Ito, and A. J. Freeman, 2009a, “Giant modification of the magnetocrystalline anisotropy in transition-metal monolayers by an external electric field,” Phys. Rev. Lett. 102, 187201.
  185. Nakamura, K., R. Shimabukuro, Y. Fujiwara, T. Akiyama, T. Ito, and A. J. Freeman, 2009b, “Origin of electric-field-induced modification of magnetocrystalline anisotropy at Fe(001) surfaces: Mechanism of dipole formation from first principles,” Phys. Rev. B 80, 172402.
  186. Natarajarathinam, A., Z. R. Tadisina, T. Mewes, S. Watts, E. Chen, and S. Gupta, 2012, “Influence of capping layers on CoFeB anisotropy and damping,” J. Appl. Phys. 112, 053909.
  187. Néel, L., 1954, “Anisotropie magnétique superficielle et surstructures d’orientation,” J. Phys. Radium 15, 225–239.
  188. Nguyen, P. P, and Y. Huai, 2004, “Spin transfer magnetic element with free layers having high perpendicular anisotropy and in-plane equilibrium magnetization,” Patent application US 7,531,882B2.
  189. Niranjan, M. K., C.-G. Duan, S. S. Jaswal, and E. Y. Tsymbal, 2010, “Electric field effect on magnetization at the Fe/MgO(001) interface,” Appl. Phys. Lett. 96, 222504.
  190. Nistor, L. E., B. Rodmacq, S. Auffret, and B. Dieny, 2009, “Pt/Co/oxide and oxide/Co/Pt electrodes for perpendicular magnetic tunnel junctions,” Appl. Phys. Lett. 94, 012512.
  191. Nistor, L. E., B. Rodmacq, C. Ducruet, C. Portemont, I. L. Prejbeanu, and B. Dieny, 2010, “Correlation between perpendicular anisotropy and magnetoresistance in magnetic tunnel junctions,” IEEE Trans. Magn. 46, 1412–1415.
  192. Nogues, J., and I. K. Schuller, 1999, “Exchange bias,” J. Magn. Magn. Mater. 192, 203.
  193. Nowak, J. J., et al., 2011, “Demonstration of ultralow bit error rates for spin-torque magnetic random access memory with perpendicular anisotropy,” IEEE Magn. Lett. 2, 3000204.
  194. Nozaki, T., Y. Shiota, T. Shiraishi, T. Shinjo, and Y. Suzuki, 2010, “Voltage-induced perpendicular magnetic anisotropy in magnetic tunnel junctions,” Appl. Phys. Lett. 96, 022506.
  195. Oh, Y. W., K. D. Lee, J. R. Jeong, and B. G. Park, 2014, “Interfacial perpendicular magnetic anisotropy in CoFeB/MgO structure with various underlayers,” J. Appl. Phys. 115, 17C724.
  196. Okabayashi, J., J. W. Koo, H. Sukegawa, S. Mitani, Y. Takagi, and T. Yokoyama, 2014, Appl. Phys. Lett. 105, 122408.
  197. Ortiz Pauyac, C., X. Wang, M. Chshiev, and A. Manchon, 2013, “Angular dependence and symmetry of Rashba spin torque in ferromagnetic heterostructures,” Appl. Phys. Lett. 102, 252403.
  198. Pai, C.-F., L. Liu, Y. Li, H. W. Tseng, D. C. Ralph, and R. A. Buhrman, 2012, “Spin transfer torque devices utilizing the giant spin Hall effect of tungsten,” Appl. Phys. Lett. 101, 122404.
  199. Papusoi, C., B. Delaët, B. Rodmacq, D. Houssameddine, J.-P. Michel, U. Ebels, R. C. Sousa, L. D. Buda-Prejbeanu, and B. Dieny, 2009, “100 ps precessional spin transfer switching of a planar magnetic random access memory cell with perpendicular spin polarizer,” Appl. Phys. Lett. 95, 072506.
  200. Park, J. G., T. H. Shim, K. S. Chae, D. Y. Lee, Y. Takemura, S. E. Lee, M. S. Jeon, J. U. Baek, S. O. Park, and J. P. Hong, 2014, “Challenging issues for Terra-bit level perpendicular STT-MRAM,” Electron Devices Meeting, (IEDM), 2014 IEEE International, pp. 19.2.1–19.2.4.
  201. Parkin, S. S. P., M. Hayashi, and L. Thomas, 2008, “Magnetic domain-wall racetrack memory,” Science 320, 190–194.
  202. Parkin, S. S. P., C. Kaiser, A. Panchula, P. M. Rice, B. Hughes, M. Samant, and S. H. Yang, 2004, “Giant tunnel magnetoresistance at room temperature with MgO(100) tunnel barriers,” Nat. Mater. 3, 862–867.
  203. Parkin, S. S. P., N. More, and K. P. Roche, 1990, “Oscillations in exchange coupling and magnetoresistance in metallic structures: Co/Ru, Co/Cr and Fe/Cr,” Phys. Rev. Lett. 64, 2304–2307.
  204. Peng, S. Z., et al., 2015, “Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures,” Sci. Rep. 5, 18173.
  205. Pesin, D. A., and A. H. MacDonald, 2012, “Quantum kinetic theory of current-induced torques in Rashba ferromagnets,” Phys. Rev. B 86, 014416.
  206. Pi, U. H., et al., 2010, “Tilting of the spin orientation induced by Rashba effect in ferromagnetic metal layer,” Appl. Phys. Lett. 97, 162507.
  207. Piramanayagama, S. N., 2007, “Perpendicular recording media for hard disk drives,” J. Appl. Phys. 102, 011301.
  208. Prejbeanu, I. L., M. Kerekes, R. C. Sousa, H. Sibuet, O. Redon, B. Dieny, and J.-P. Nozières, 2007, “Thermally Assisted MRAM,” J. Phys. Condens. Matter 19, 165218.
  209. Prinz, G. A., 1985, “Stabilization of bcc Co via epitaxial growth on GaAs,” Phys. Rev. Lett. 54, 1051–1054.
  210. Rajanikanth, A., T. Hauet, F. Montaigne, S. Mangin, and S. Andrieu, 2013, “Magnetic anisotropy modified by electric field in V/Fe/MgO(001)/Fe epitaxial magnetic tunnel junction,” Appl. Phys. Lett. 103, 062402.
  211. Rantschler, J. O., R. D. McMichael, A. Castillo, A. J. Shapiro, J. W. F. Egelhoff, B. B. Maranville, D. Pulugurtha, A. P. Chen, and L. M. Connors, 2007, “Effect of 3d, 4d, and 5d transition metal doping on damping in permalloy thin films,” J. Appl. Phys. 101, 033911.
  212. Ravelosona, D., C. Chappert, V. Mathet, and H. Bernas, 2000, “Chemical order induced by ion irradiation in FePt(001) films,” Appl. Phys. Lett. 76, 236–238.
  213. Redon, O., B. Dieny, and B. Rodmacq, 2000, “Magnetic spin polarization and magnetization rotation device with memory and writing process using such device,” Patent Application US 6,532,164B2.
  214. Reig, C., S. Cardoso de Freitas, and S. C. Mukhopadhyay, 2014, Eds., Giant Magnetoresistance (GMR) Sensors: From Basis to State-of-the-Art Applications (Springer, New York).
  215. Rippard, W. H., M. R. Pufall, S. Kaka, T. J. Silva, S. E. Russek, and J. A. Katine, 2005, “Injection locking and phase control of spin transfer nano-oscillators,” Phys. Rev. Lett. 95, 067203.
  216. Rizzo, N. D., et al., 2013, “A fully functional 64 Mb DDR3 ST-MRAM built on 90 nm CMOS technology,” IEEE Trans. Magn. 49, 4441–4446.
  217. Rodmacq, B., S. Auffret, B. Dieny, S. Monso, and P. Boyer, 2003, “Crossovers from in-plane to perpendicular anisotropy in magnetic tunnel junctions as a function of the barrier degree of oxidation,” J. Appl. Phys. 93, 7513–7515.
  218. Rodmacq, B., S. Auffret, B. Dieny, and L. E. Nistor, 2008, “Three-layer magnetic element, magnetic field sensor, magnetic memory and magnetic logic gate using such an element,” Patent Application US 8,513,944B2.
  219. Rodmacq, B., and B. Dieny, 2006, “Thin-layered magnetic device with high spin polarization perpendicular to the plane of the layers, and magnetic tunnel junction and spin valve using such a device,” Patent Application US 7,813,202B2.
  220. Rodmacq, B., A. Manchon, C. Ducruet, S. Auffret, and B. Dieny, 2009, “Influence of thermal annealing on the magnetic properties of Pt/Co/AlOx trilayers,” Phys. Rev. B 79, 024423.
  221. Roessler, U. K., A. N. Bogdanov, and C. Pfleiderer, 2006, “Spontaneous skyrmion ground states in magnetic metals,” Nature (London) 442, 797–801.
  222. Rossnagel, S. M., and H. Kim, 2003, “Diffusion barrier properties of very thin TaN with high nitrogen concentration,” J. Vac. Sci. Technol. B 21, 2550–2554.
  223. Saitoh, E., M. Ueda, H. Miyajima, and G. Tatara, 2006, “Conversion of spin current into charge current at room temperature: Inverse spin-Hall effect,” Appl. Phys. Lett. 88, 182509.
  224. Sampaio, J., V. Cros, S. Rohart, A. Thiaville, and A. Fert, 2013, “Nucleation, stability and current-induced motion of isolated magnetic skyrmions in nanostructures,” Nat. Nanotechnol. 8, 839–844.
  225. Sankar, S., B. Dieny, and A. Berkowitz, 1997, “Spin-polarized tunnelling in discontinuous CoFe/HfO2 multilayers,” J. Appl. Phys. 81, 5512–5514.
  226. Sato, H., T. Yamamoto, M. Yamanouchi, S. Ikeda, S. Fukami, K. Kinoshita, F. Matsukura, N. Kasai, and H. Ohno, 2014, “Comprehensive study of CoFeB-MgO magnetic tunnel junction characteristics with single- and double-interface scaling down to 1X nm,” Electron Devices Meeting (IEDM), 2013 IEEE International, pp. 33.2.1–33.2.4.
  227. Sato, H., M. Yamanouchi, K. Miura, S. Ikeda, H. D. Gan, K. Mizunuma, R. Koizumi, F. Matsukura, and H. Ohno, 2011, “Junction size effect on switching current and thermal stability in CoFeB/MgO perpendicular magnetic tunnel junctions,” Appl. Phys. Lett. 99, 042501.
  228. Savtchenko, L., B. Engels, N. Rizzo, M. DeHerrera, and J. A. Janesky, 2003, “Method of writing to scalable magnetoresistance random access memory element,” Patent Application US 6,545,906.
  229. Sbiaa, R., H. Meng, and S. N. Piramanayagam, 2011, “Materials with perpendicular magnetic anisotropy for magnetic random access memory,” Phys. Status Solidi RRL 5, 413–419.
  230. Scheck, C., L. Cheng, I. Barsukov, Z. Frait, and W. E. Bailey, 2007, “Low relaxation rate in epitaxial vanadium-doped ultrathin iron films,” Phys. Rev. Lett. 98, 117601.
  231. Schellekens, A. J., A. van den Brink, J. H. Franken, H. J. M. Swagten, and B. Koopmans, 2012, “Electric-field control of domain wall motion in perpendicularly magnetized materials,” Nat. Commun. 3, 847.
  232. Seki, T., M. Kohda, J. Nitta, and K. Takanashi, 2011, “Coercivity change in an FePt thin layer in a Hall device by voltage application,” Appl. Phys. Lett. 98, 212505.
  233. Shaw, J. M., H. T. Nembach, and T. J. Silva, 2012, “Determination of spin pumping as a source of linewidth in sputtered Co90Fe10/Pd multilayers by use of broadband ferromagnetic resonance spectroscopy,” Phys. Rev. B 85, 054412.
  234. Shaw, J. M., H. T. Nembach, M. Weiler, T. J. Silva, M. Schoen, J. Z. Sun, and D. C. Worledge, 2015, “Perpendicular Magnetic Anisotropy and Easy Cone State in Ta/Co60Fe20B20/MgO,” IEEE Magn. Lett. 6, 3500404.
  235. Shimabukuro, R., K. Nakamura, T. Akiyama, and T. Ito, 2010, “Electric field effects on magnetocrystalline anisotropy in ferromagnetic Fe monolayers,” Physica E: Low-dimens. Syst. Nanostruct. 42, 1014–1017.
  236. Shiota, Y., T. Maruyama, T. Nozaki, T. Shinjo, M. Shiraishi, and Y. Suzuki, 2009, “Voltage-assisted magnetization switching in ultrathin Fe80Co20 alloy layers,” Appl. Phys. Express 2, 063001.
  237. Shiota, Y., T. Nozaki, F. Bonell, S. Murakami, T. Shinjo, and Y. Suzuki, 2012, “Induction of coherent magnetization switching in a few atomic layers of FeCo using voltage pulses,” Nat. Mater. 11, 39–43.
  238. Sicot, M., S. Andrieu, F. Bertran, and F. Fortuna, 2005, “Electronic properties of Fe, Co, and Mn ultrathin films at the interface with MgO(001),” Phys. Rev. B 72, 144414.
  239. Sinha, J., et al., 2013, “Enhanced interface perpendicular magnetic anisotropy in Ta/CoFeB/MgO using nitrogen doped Ta underlayers,” Appl. Phys. Lett. 102, 242405.
  240. Skomski, R., 1998, “Magnetoelectric Néel anisotropies,” IEEE Trans. Magn. 34, 1207–1209.
  241. Skomski, R., A. Kashyap, A. Solanki, A. Enders, and D. J. Sellmyer, 2010, “Magnetic anisotropy in itinerant magnets,” J. Appl. Phys. 107, 09A735.
  242. Slonczewski, J. C., 1996, “Current driven excitations of magnetic multilayers,” J. Magn. Magn. Mater. 159, L1–L7.
  243. Slonczewski, J. C., 1999, “Excitation of spin waves by an electric current,” J. Magn. Magn. Mater. 195, L261–L268.
  244. Sokalski, V., M. T. Moneck, E. Yang, and J. G. Zhu, 2012, “Optimization of Ta thickness for perpendicular magnetic tunnel junction applications in the MgO-FeCoB-Ta system,” Appl. Phys. Lett. 101, 072411.
  245. Stainer, Q., L. Lombard, K. Mackay, D. Lee, S. Bandiera, C. Portemont, C. Creuzet, R. C. Sousa, and B. Dieny, 2014, “Self-referenced multi-bit thermally assisted magnetic random access memories,” Appl. Phys. Lett. 105, 032405.
  246. Stipe, B., et al., 2010, “Magnetic recording at 1.5  Pb/m2 using an integrated plasmonic antenna,” Nat. Photonics 4, 484–488.
  247. Suess, D., T. Schrefl, S. Fähler, M. Kirschner, G. Hrkac, F. Dorfbauer, and J. Fidler, 2005, “Exchange spring media for perpendicular recording,” Appl. Phys. Lett. 87, 012504.
  248. Sugita, Y., Y. Kawawake, M. Satomi, and H. Sakakima, 2001, “Thermal stability of PtMn based synthetic spin valves using thin oxide layer,” J. Appl. Phys. 89, 6919–6921.
  249. Sun, J. Z., 2000, “Spin-current interaction with a monodomain magnetic body: A model study,” Phys. Rev. B 62, 570–578.
  250. Sun, J. Z., 2006, “Spin angular momentum transfer in current-perpendicular nanomagnetic junctions,” IBM J. Res. Dev. 50, 81–100.
  251. Suzuki, S., S. Yasuda, K. Edakawa, and S. Seki, 2013, “First-principles study of electric field effects on magnetic anisotropy in MgO/TM/Au (TM = Fe, Co) systems,” J. Phys. Soc. Jpn. 82, 124715.
  252. Suzuki, T., et al., 2011, “Current-induced effective field in perpendicularly magnetized Ta/CoFeB/MgO wire,” Appl. Phys. Lett. 98, 142505.
  253. Takayama, H., K.-P. Bohnen, and P. Fulde, 1976, “Magnetic surface anisotropy of transition metals,” Phys. Rev. B 14, 2287–2295.
  254. Tartaj, P., M. P. Morales, T. González-Carreño, S. Veintemillas-Verdaguer, and C. J. Serna, 2005, “Advances in magnetic nanoparticles for biotechnology applications,” J. Magn. Magn. Mater. 290–291, 28–34.
  255. Thiaville, A., S. Rohart, E. Jué, V. Cros, and A. Fert, 2012, “Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films,” Europhys. Lett. 100, 57002.
  256. Thomas, L., et al., 2014, “Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications,” J. Appl. Phys. 115, 172615.
  257. Thompson, D. A., and J. S. Best, 2000, “The future of magnetic data storage technology,” IBM J. Res. Dev. 44, 311–332.
  258. Timopheev, A., R. Sousa, M. Chshiev, H. T. Nguyen, and B. Dieny, 2016, “Second order anisotropy contribution in perpendicular magnetic tunnel junctions,” Sci. Rep. 6, 26877.
  259. Tomita, H., et al., 2013, “Unified understanding of both thermally assisted and precessional spin-transfer switching in perpendicularly magnetized giant magnetoresistive nanopillars,” Appl. Phys. Lett. 102, 042409.
  260. Tsai, C. C., C. W. Cheng, M. C. Tsai, and G. Chern, 2014, “Superparamagnetic states and perpendicular magnetic anisotropy in ultrathin MgO/CoFeB/Ta structures,” IEEE Trans. Magn. 50, 1401404.
  261. Tsai, W. C., S. C. Liao, H. C. Hou, C. T. Yen, Y. H. Wang, H. M. Tsai, F. H. Chang, H. J. Lin, and C. H. Lai, 2012, “Investigation of perpendicular magnetic anisotropy of CoFeB by X-ray magnetic circular dichroism,” Appl. Phys. Lett. 100, 172414.
  262. Tserkovnyak, Y., A. Brataas, and G. E. W. Bauer, 2002, “Spin pumping and magnetization dynamics in metallic multilayers,” Phys. Rev. B 66, 224403.
  263. Tsoi, M., A. G. M. Jansen, J. Bass, W.-C. Chiang, M. Seck, V. Tsoi, and P. Wyder, 1998, “Excitation of a magnetic multilayer by an electric current,” Phys. Rev. Lett. 80, 4281–4284.
  264. Tsujikawa, M., S. Haraguchi, T. Oda, Y. Miura, and M. Shirai, 2011, “A comparative ab initio study on electric-field dependence of magnetic anisotropy in MgO/Fe/Pt and MgO/Fe/Au films,” J. Appl. Phys. 109, 07C107.
  265. Tsujikawa, M., and T. Oda, 2009, “Finite electric field effects in the large perpendicular magnetic anisotropy surface Pt/Fe/Pt(001): A first-principles study,” Phys. Rev. Lett. 102, 247203.
  266. Tsunegi, S., H. Kubota, S. Tamaru, K. Yakushiji, M. Konoto, A. Fukushima, T. Tanigushi, H. Arai, H. Imamura, and S. Yuasa, 2014, “Damping parameter and interfacial perpendicular magnetic anisotropy of FeB nanopillar sadwhiched between MgO barrier and cap layers in magnetic tunnel junctions,” Appl. Phys. Express 7, 033004.
  267. Újfalussy, B., L. Szunyogh, P. Bruno, and P. Weinberger, 1996, “First-principles calculation of the anomalous perpendicular anisotropy in a Co monolayer on Au(111),” Phys. Rev. Lett. 77, 1805–1808.
  268. Vadapoo, R., A. Hallal, H. X. Yang, and M. Chshiev, 2016, “First-principles investigation of magnetocrystalline anisotropy at the L21 full Heusler|MgO inerfaces and tunnel junctions,” Phys. Rev. B 94, 104418.
  269. van der Laan, G, 1998, “Microscopic origin of magnetocrystalline anisotropy in transition metal thin films,” J. Phys. Condens. Matter 10, 3239.
  270. Varga, L., and W. D. Doyle, 1996, “Measurement of the crystalline anisotropy in sputtered single crystal FeTaN thin films,” J. Appl. Phys. 79, 4995–4997.
  271. Vedyayev, A., N. Strelkov, M. Chshiev, N. Ryzhanova, and B. Dieny, 2011, “Spin transfer torques induced by spin Hall effect,” arXiv:1108.2589v1.
  272. Veloso, A., P. P. Freitas, P. Wei, N. P. Barradas, J. C. Soares, B. Almeida, and J. B. Sousa, 2000, “Magnetoresistance enhancement in specular, bottom-pinned, Mn83Ir17 spin valves with nano-oxide layers,” Appl. Phys. Lett. 77, 1020–1022.
  273. Vo-Van, C., et al., 2010, “Ultrathin epitaxial cobalt films on graphene for spintronic investigations and applications,” New J. Phys. 12, 103040.
  274. Wang, C. L., S. H. Huang, C. H. Lai, W. C. Chen, S. Y. Yang, K. H. Shen, and H. Y. Bor, 2009, “Reduction in critical current density by tuning damping constants of CoFeB for spin torque transfer switching,” J. Phys. D 42, 115006.
  275. Wang, D.-S., R. Wu, and A. J. Freeman, 1993a, “Magnetocrystalline anisotropy of Co-Pd interfaces,” Phys. Rev. B 48, 15886–15892.
  276. Wang, D.-S., R. Wu, and A. J. Freeman, 1993b, “First-principles theory of surface magnetocrystalline anisotropy and the diatomic-pair model,” Phys. Rev. B 47, 14932–14947.
  277. Wang, W-G., M. Li, S. Hageman, and C. L. Chien, 2012, “Electric-field-assisted switching in magnetic tunnel junctions,” Nat. Mater. 11, 64–68.
  278. Wang, K.-L., H. Lee, and P. K. Amiri, 2015, “Magnetoelectric Random Access Memory-Based Circuit Design by Using Voltage-Controlled Magnetic Anisotropy in Magnetic Tunnel Junctions,” IEEE Trans. Nanotechnol. 14, 992.
  279. Wang, X., and A. Manchon, 2012, “Diffusive spin dynamics in ferromagnetic thin films with a Rashba interaction,” Phys. Rev. Lett. 108, 117201.
  280. Wang, X. D., D. S. Wang, R. Q. Wu, and A. J. Freeman, 1996, “Validity of the force theorem for magnetocrystalline anisotropy,” J. Magn. Magn. Mater. 159, 337–341.
  281. Wegrowe, J. E., D. Kelly, Y. Jaccard, P. Guittienne, and J.-P. Ansermet, 1999, “Current-induced magnetization reversal in magnetic nanowires,” Europhys. Lett. 45, 626–632.
  282. Weinert, M., R. E. Watson, and J. W. Davenport, 1985, “Total-energy differences and eigenvalue sums,” Phys. Rev. B 32, 2115–2119.
  283. Weisheit, M., S. Fähler, A. Marty, Y. Souche, C. Poinsignon, and D. Givord, 2007, “Electric field-induced modification of magnetism in thin-film ferromagnets,” Science 315, 349–351.
  284. Wolf, S. A., J. Lu, M. R. Stan, E. Chen, and D. M. Treger, 2010, “The promise of nanomagnetics and spintronics for future logic and universal memory,” Proc. IEEE 98, 2155–2168.
  285. Worledge, D. C., 2010, “Seed layer and free magnetic layer for perpendicular anisotropy in a spin-torque magnetic random access memory,” Patent Application US 0,303,995A1.
  286. Worledge, D. C., G. Hu, D. Abraham, J. Z. Sun, P. L. Trouilloud, J. Nowak, S. Brown, M. C. Gaidis, E. J. O’Sullivan, and R. P. Robertazzi, 2011, “Spin torque switching of perpendicular Ta/CoFeB/MgO-based magnetic tunnel junctions,” Appl. Phys. Lett. 98, 022501.
  287. Worledge, D. C., G. Hu, D. W. Abraham, P. L. Trouilloud, and S. Brown, 2014, “Development of perpendicularly magnetized Ta/CoFeB/MgO-based tunnel junctions at IBM,” J. Appl. Phys. 115, 172601.
  288. Worledge, D. C., and P. L. Trouilloud, 2003, “Magnetoresistance measurement of unpatterned magnetic tunnel junction wafers by current-in-plane tunnelling,” Appl. Phys. Lett. 83, 84–86.
  289. Wu, R., and A. J. Freeman, 1999, “Spin-orbit induced magnetic phenomena in bulk metals and their surfaces and interfaces,” J. Magn. Magn. Mater. 200, 498–514.
  290. Yakata, S., H. Kubota, Y. Suzuki, K. Yakushiji, A. Fukushima, S. Yuasa, and K. Ando, 2009, “Influence of perpendicular magnetic anisotropy on spin transfer switching current in CoFeB/MgO/CoFeB magnetic tunnel junctions,” J. Appl. Phys. 105, 07D131.
  291. Yakushiji, K., T. Saruya, H. Kubota, A. Fukushima, T. Nagahama, S. Yuasa, and K. Ando, 2010, “Ultrathin Co/Pt and Co/Pd superlattice films for MgO-based perpendicular magnetic tunnel junctions,” Appl. Phys. Lett. 97, 232508.
  292. Yamanouchi, M., L. Chen, J. Kim, M. Hayashi, H. Sato, S. Fukami, S. Ikeda, F. Matsukura, and H. Ohno, 2013, “Three terminal magnetic tunnel junction utilizing the spin Hall effect of iridium-doped copper,” Appl. Phys. Lett. 102, 212408.
  293. Yang, H. X., 2012, “First-principles study of spintronic phenomena in magnetic tunnel junctions and graphene,” Ph.D. thesis, University of Grenoble.
  294. Yang, H. X., M. Chshiev, B. Dieny, J. H. Lee, A. Manchon, and K. H. Shin, 2011, “First principles investigation of the very large perpendicular magnetic anisotropy at Fe|MgO and Co|MgO interfaces,” Phys. Rev. B 84, 054401.
  295. Yang, H. X., A. Thiaville, S. Rohart, A. Fert, and M. Chshiev, 2015, “Anatomy of Dzyaloshinskii-Moriya Interaction at Co/Pt Interfaces,” Phys. Rev. Lett. 115, 267210.
  296. Yang, H. X., A. D. Vu, A. Hallal, N. Rougemaille, J. Coraux, G. Chen, A. K. Schmid, and M. Chshiev, 2016, “Anatomy and Giant Enhancement of the Perpendicular Magnetic Anisotropy of Cobalt-Graphene Heterostructures,” Nano Lett. 16, 145.
  297. Yang, I., S. Y. Savrasov, and G. Kotliar, 2001, “Importance of Correlation Effects on Magnetic Anisotropy in Fe and Ni,” Phys. Rev. Lett. 87, 216405.
  298. Yang, S., J. Lee, G. An, J. Kim, W. Chung, and J. P. Hong, 2014, “Thermally stable perpendicular magnetic anisotropy features of Ta/TaOx/Ta/CoFeB/MgO/W stacks via TaOx underlayer insertion,” J. Appl. Phys. 116, 113902.
  299. Yoda, H., S. Fujita, N. Shimomura, E. Kitagawa, K. Abe, K. Nomura, H. Noguchi, and J. Ito, 2012, “Progress of STT-MRAM technology and the effect on normally-off computing systems,” Electron Devices Meeting (IEDM), 2012 IEEE International, 11.3.1–11.3.4.
  300. Yoda, H., et al., 2010, “High efficient spin transfer torque writing on perpendicular magnetic tunnel junctions for high density MRAMs,” Curr. Appl. Phys. 10, e87–e90.
  301. You, C. Y., T. Ohkubo, Y. K. Takahashi, and K. Hono, 2008, “Boron segregation in crystallized MgO/amorphous Co40Fe40B20 thin films,” J. Appl. Phys. 104, 033517.
  302. Yu, G., et al., 2014, “Switching of perpendicular magnetization by spin–orbit torques in the absence of external magnetic fields,” Nat. Nanotechnol. 9, 548–554.
  303. Yu, G., et al., 2015, “Strain-induced modulation of perpendicular magnetic anisotropy in Ta/CoFeB/MgO structures investigated by ferromagnetic resonance,” Appl. Phys. Lett. 106, 072402.
  304. Yu, X. Z., Y. Onose, N. Kanazawa, J. H. Park, J. H. Han, Y. Matsui, N. Nagaosa, and Y. Tokura, 2010, “Real-space observation of a two-dimensional skyrmion crystal,” Nature (London) 465, 901–904.
  305. Yuasa, S., and D. D. Djayaprawira, 2007, “Giant tunnel magnetoresistance in magnetic tunnel junctions with a crystalline MgO(001) barrier,” J. Phys. D 40, R337–R354.
  306. Yuasa, S., A. Fukushima, H. Kubota, Y. Suzuki, and K. Ando, 2006, “Giant tunneling magnetoresistance up to 410% at room temperature in fully epitaxial Co/MgO/Co magnetic tunnel junctions with bcc Co(001) electrodes,” Appl. Phys. Lett. 89, 042505.
  307. Yuasa, S., T. Nagahama, A. Fukushima, Y. Suzuki, and K. Ando, 2004, “Giant room temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions,” Nat. Mater. 3, 868–871.
  308. Yuasa, S., Y. Suzuki, T. Katayama, and K. Ando, 2005, “Characterization of growth and crystallization processes in CoFeB/MgO/CoFeB magnetic tunnel junction structure by reflective high energy electron diffraction,” Appl. Phys. Lett. 87, 242503.
  309. Zhang, J., C. Franz, M. Czerner, and C. Heiliger, 2014, “Perpendicular magnetic anisotropy in CoFe/MgO/CoFe magnetic tunnel junctions by first-principles calculations,” Phys. Rev. B 90, 184409.
  310. Zhang, S., and Z. Li, 2004, “Roles of non-equilibrium conduction electrons on the magnetization dynamics of ferromagnets,” Phys. Rev. Lett. 93, 127204.
  311. Zhang, X.-G., W. H. Butler, and A. Bandyopadhyay, 2003, “Effects of the iron-oxide layer in Fe-FeO-MgO-Fe tunneling junctions,” Phys. Rev. B 68, 092402.
  312. Zhu, J., et al., 2012, “Voltage-Induced Ferromagnetic Resonance in Magnetic Tunnel Junctions,” Phys. Rev. Lett. 108, 197203.
  313. Zhu, J. G., X. Zhu, and Y. Tang, 2008, “Microwave-assisted magnetic recording,” IEEE Trans. Magn. 44, 125–131.
  314. Zhu, W., D. Xiao, Y. Liu, S. J. Gong, and C.-G. Duan, 2014, “Picosecond electric field pulse induced coherent magnetic switching in MgO/FePt/Pt(001)-based tunnel junctions: A multiscale study,” Sci. Rep. 4, 4117.

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Rev. Mod. Phys. 89, 025008– Published 28 June, 2017
  • Received 7 May 2015

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