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HIGHLIGHTED ARTICLES

Self-focusing skyrmion racetracks in ferrimagnets

Se Kwon Kim, Kyung-Jin Lee, and Yaroslav Tserkovnyak

Phys. Rev. B 95, 140404(R) (2017) - Published 14 April, 2017

Skyrmions, swirling magnetic textures with a topological character, have been gaining much attention in spintronics due to the fundamental interest as well as their touted utility as information carriers in ultradense and low-power memory devices. Generally, a skyrmion behaves as a massive particle moving in a viscous medium and experiencing a Magnus force, which is proportional to its winding number and the spin polarization of the magnet. There is a class of tunable ferrimagnets, such as rare-earth transition-metal alloys, exhibiting the angular momentum compensation point at which the spin density changes sign. This raises the possibility to engineer both the magnitude and the sign of the Magnus force acting on the skyrmions in the ferrimagnets. The authors exploit this to suggest that ferrimagnetic skyrmions can exhibit snake trajectories along the line of the vanishing spin density, analogous to the snake orbits of electrons in a nonuniform magnetic field. This can be utilized as dynamically self-focusing racetracks for skyrmions, paving the way for skyrmion-based memory devices.

Effects of grain boundaries and defects on anisotropic magnon transport in textured Sr14Cu24O41

Xi Chen, Karalee Jarvis, Sean Sullivan, Yutao Li, Jianshi Zhou, and Li Shi

Phys. Rev. B 95, 144310 (2017) - Published 27 April, 2017

The strong spin-spin exchange interaction in some low-dimensional magnetic materials can give rise to a high group velocity and thermal conductivity contribution from magnons, which are energy quanta of collective spin excitations. Examples are the incommensurate layered compounds (Sr,Ca,La)14Cu24O41, with strong antiferromagnetic interaction along the ladders. The effects of grain boundaries and defects on quasi-one-dimensional magnon transport in these compounds are not well understood. Here, the authors report the microstructures and anisotropic thermal transport properties of textured Sr14Cu24O41. TEM clearly reveals nanolayered grains and the presence of dislocations and planar defects. The thermal conductivity contribution and mean free paths of magnons in the textured samples are evaluated with the use of a kinetic model for one-dimensional magnon transport, and found to be suppressed significantly compared to single crystals at low temperatures. The experimental results can be explained by a one-dimensional magnon-defect scattering model, provided that the magnon–grain boundary scattering mean free path in the anisotropic magnetic structure is smaller than the average length of these nanolayers along the c axis. The finding suggests low transmission coefficients for energy-carrying magnons across grain boundaries.

Spin superfluid Josephson quantum devices

So Takei, Yaroslav Tserkovnyak, and Masoud Mohseni

Phys. Rev. B 95, 144402 (2017) - Published 4 April, 2017

Spin Hall phenomena are a collection of relativistic spin-orbit coupling effects that permit control and detection of magnetization dynamics in magnetic materials with electrical currents. In spintronics, they have been studied extensively in bilayer structures consisting of a magnetically ordered material interfaced by a current-carrying paramagnetic metal with strong spin-orbit coupling. In this work, the authors propose the magnetic phase qubit, the macroscopic quantum spintronic device that can be built from such bilayers and that permits full electrical control and readout via spin Hall phenomena. The device is an example of a macroscopic qubit that can be constructed from solid-state materials and so should offer the same advantages as the superconducting qubits of strong inter-qubit coupling and scalability. An estimate of the relevant physical parameters based on current spintronic technology gives a qubit operational temperature that is more than an order of magnitude higher than for existing superconducting qubits, thus opening the possibility of macroscopic quantum information processing at temperatures above the dilution refrigerator range. The authors also show that a coupled array of these qubits can realize a quantum annealer, which could be used to solve certain hard optimization problems and machine learning tasks.

Counter-rotating standing spin waves: A magneto-optical illusion

S. Shihab, L. Thevenard, A. Lemaître, and C. Gourdon

Phys. Rev. B 95, 144411 (2017) - Published 12 April, 2017

In ferromagnetic layers, spin-wave modes can be excited by a laser pulse launching the magnetization out of equilibrium and into precession. The trajectory of the magnetization vector can be fully reconstructed using different magneto-optical effects, generally admitted to give a faithful picture of the dynamics. The authors show that this is not always the case and that magneto-optical effects can indeed be deceiving. For this, they study the case of a weakly absorbing ferromagnet, the semiconductor GaMnAs, in which perpendicular standing spin waves are excited by a laser pulse. Quite counterintuitively, the optical detection shows the first two excited modes to be of opposite chirality, whereas theory tells us the spin waves actually rotate in the same direction. The paper demonstrates that this unexpected and surprising effect is a pure optical illusion. It can perfectly be explained by taking into account absorption and optical phase shift inside the layer, the latter being particularly strong in weakly absorbing layers. These results provide a correct identification of spin-wave modes, enabling a trustworthy estimation of their respective weight as well as an unambiguous determination of the spin stiffness parameter.

Single-ion properties of the Seff = 12 XY antiferromagnetic pyrochlores NaACo2F7 (A=Ca2+, Sr2+)

K. A. Ross, J. M. Brown, R. J. Cava, J. W. Krizan, S. E. Nagler, J. A. Rodriguez-Rivera, and M. B. Stone

Phys. Rev. B 95, 144414 (2017) - Published 13 April, 2017

Quantum effects in magnetic materials are prevalent when the magnetic ions support spin-½ moments, as in Cu2+-based materials. Strong quantum effects can also be achieved when the large angular momentum states are reduced to an effective spin-½ subspace (Seff=½) by the combined effect of spin-orbit coupling and the crystal electric field. A consequence of this is the introduction of anisotropy to the g tensor and the effective exchange interactions. Such anisotropic Seff=½ models have recently been applied successfully to rare-earth based frustrated pyrochlore materials, where they are found to lead to particularly rich phenomenology for XY-like g tensors. Here, it is shown that a similar quantum model should apply to the recently discovered “high temperature” Co2+ pyrochlores, NaCaCo2F7 and NaSrCo2F7, based on a fit to their single ion levels as measured via inelastic neutron scattering. The effect of the intrinsic crystalline disorder on the anisotropy of the Seff=½ moments in these materials is also estimated.

Spin superfluidity and spin waves in YIG films

E. B. Sonin

Phys. Rev. B 95, 144432 (2017) - Published 27 April, 2017

Recently, it was suggested that metastable spin supercurrents (spin superfluidity) are possible in the magnon condensate observed in yttrium iron garnet (YIG) magnetic films under strong magnon pumping. In YIG, magnetic anisotropy is rather weak, and this material can be treated as an isotropic ferromagnet. Its order-parameter space is a sphere of radius equal to the spontaneous magnetization M. A current state maps on the equatorial circumference on the sphere, and topology of the sphere allows us to continuously transform the equatorial circumference to the point. This rules out metastable current states. Only easy-plane anisotropy reducing the order-parameter space from the sphere to the equatorial circumference makes current states topologically stable. However, by pumping magnons to the isotropic ferromagnet in a magnetic field, it is possible to support a strongly nonequilibrium state with fixed average Mz. This confines the precessing spin to an “easy plane” of dynamical rather than topological origin and makes metastable spin currents possible. But final judgment requires evaluation of the Landau superfluidity criterion as done in the present work. The conclusion is that spin superfluidity in YIG films is possible in principle, although the recently published claim of its observation is not justified.

Universality of the helimagnetic transition in cubic chiral magnets: Small angle neutron scattering and neutron spin echo spectroscopy studies of FeCoSi

L. J. Bannenberg, K. Kakurai, P. Falus, E. Lelièvre-Berna, R. Dalgliesh, C. D. Dewhurst, F. Qian, Y. Onose, Y. Endoh, Y. Tokura, and C. Pappas

Phys. Rev. B 95, 144433 (2017) - Published 28 April, 2017

Chiral magnetism plays an increasingly important role in condensed matter investigations driven by the discovery of exotic spin textures, such as the topologically protected chiral skyrmions that can form a lattice under magnetic fields. The nature and universality of the phase diagram in cubic chiral magnets has been the subject of numerous experimental and theoretical investigations, including the transition to the helimagnetic state. In MnSi, the archetypal system in this family, this transition is of first order and involves a precursor phase, where strong chiral fluctuating correlations build up. This work presents an experimental investigation of the structural and dynamical aspects of the phase transition in Fe1-xCoxSi, a system that belongs to the same family as MnSi but with the additional possibility to tune important physical interactions and parameters through variation of the Fe and Co concentration. In this system, the combination of small-angle neutron scattering and neutron spin echo spectroscopy uncovers that the scenario of the transition is qualitatively very different from that in MnSi. This goes beyond what can be expected from a comparison of the relevant length scales and thus challenges the validity of a universal approach to the helimagnetic transition in cubic chiral magnets.

RAPID COMMUNICATIONS

Structure, structural phase transitions, mechanical properties, defects

Stable high-pressure phases in the H-S system determined by chemically reacting hydrogen and sulfur

Alexander F. Goncharov, Sergey S. Lobanov, Vitali B. Prakapenka, and Eran Greenberg

Phys. Rev. B 95, 140101(R) (2017) - Published 10 April, 2017

Inhomogeneous, disordered, and partially ordered systems

Effect of a bias field on disordered waveguides: Universal scaling of conductance and application to ultracold atoms

Cécile Crosnier de Bellaistre, Alain Aspect, Antoine Georges, and Laurent Sanchez-Palencia

Phys. Rev. B 95, 140201(R) (2017) - Published 4 April, 2017

Quasiparticle interference and resonant states in normal and superconducting line nodal semimetals

Chandan Setty, Philip W. Phillips, and Awadhesh Narayan

Phys. Rev. B 95, 140202(R) (2017) - Published 27 April, 2017

Magnetism

Concomitant antiferromagnetic transition and disorder-induced weak localization in an interacting electron system

Tanmoy Ghosh, Takashi Fukuda, Tomoyuki Kakeshita, S. N. Kaul, and P. K. Mukhopadhyay

Phys. Rev. B 95, 140401(R) (2017) - Published 3 April, 2017

Magnon planar Hall effect and anisotropic magnetoresistance in a magnetic insulator

J. Liu, L. J. Cornelissen, J. Shan, T. Kuschel, and B. J. van Wees

Phys. Rev. B 95, 140402(R) (2017) - Published 10 April, 2017

Incommensurate magnetic order in a quasicubic structure of the double-perovskite compound Sr2NiIrO6

K. Rolfs, S. Tóth, E. Pomjakushina, D. T. Adroja, D. Khalyavin, and K. Conder

Phys. Rev. B 95, 140403(R) (2017) - Published 10 April, 2017

Self-focusing skyrmion racetracks in ferrimagnets

Se Kwon Kim, Kyung-Jin Lee, and Yaroslav Tserkovnyak

Phys. Rev. B 95, 140404(R) (2017) - Published 14 April, 2017

Skyrmions, swirling magnetic textures with a topological character, have been gaining much attention in spintronics due to the fundamental interest as well as their touted utility as information carriers in ultradense and low-power memory devices. Generally, a skyrmion behaves as a massive particle moving in a viscous medium and experiencing a Magnus force, which is proportional to its winding number and the spin polarization of the magnet. There is a class of tunable ferrimagnets, such as rare-earth transition-metal alloys, exhibiting the angular momentum compensation point at which the spin density changes sign. This raises the possibility to engineer both the magnitude and the sign of the Magnus force acting on the skyrmions in the ferrimagnets. The authors exploit this to suggest that ferrimagnetic skyrmions can exhibit snake trajectories along the line of the vanishing spin density, analogous to the snake orbits of electrons in a nonuniform magnetic field. This can be utilized as dynamically self-focusing racetracks for skyrmions, paving the way for skyrmion-based memory devices.

Domain-wall dynamics in magnetoelastic nanostripes

Théo Mathurin, Stefano Giordano, Yannick Dusch, Nicolas Tiercelin, Philippe Pernod, and Vladimir Preobrazhensky

Phys. Rev. B 95, 140405(R) (2017) - Published 25 April, 2017

Lattice spin models for non-Abelian chiral spin liquids

P. Lecheminant and A. M. Tsvelik

Phys. Rev. B 95, 140406(R) (2017) - Published 26 April, 2017

Superfluidity and superconductivity

Control of bulk superconductivity in a BCS superconductor by surface charge doping via electrochemical gating

E. Piatti, D. Daghero, G. A. Ummarino, F. Laviano, J. R. Nair, R. Cristiano, A. Casaburi, C. Portesi, A. Sola, and R. S. Gonnelli

Phys. Rev. B 95, 140501(R) (2017) - Published 7 April, 2017

Signatures of unconventional superconductivity in the LaAlO3/SrTiO3 two-dimensional system

D. Stornaiuolo, D. Massarotti, R. Di Capua, P. Lucignano, G. P. Pepe, M. Salluzzo, and F. Tafuri

Phys. Rev. B 95, 140502(R) (2017) - Published 7 April, 2017

P23 superfluids are topological

Takeshi Mizushima, Kota Masuda, and Muneto Nitta

Phys. Rev. B 95, 140503(R) (2017) - Published 20 April, 2017

Controlling Majorana states in topologically inhomogeneous superconductors

Pasquale Marra and Mario Cuoco

Phys. Rev. B 95, 140504(R) (2017) - Published 24 April, 2017

Signature of multigap nodeless superconductivity in CaKFe4As4

P. K. Biswas, A. Iyo, Y. Yoshida, H. Eisaki, K. Kawashima, and A. D. Hillier

Phys. Rev. B 95, 140505(R) (2017) - Published 24 April, 2017

Driving topological phases by spatially inhomogeneous pairing centers

Wojciech Brzezicki, Andrzej M. Oleś, and Mario Cuoco

Phys. Rev. B 95, 140506(R) (2017) - Published 25 April, 2017

Dissipation in mesoscale superfluids

Adrian Del Maestro and Bernd Rosenow

Phys. Rev. B 95, 140507(R) (2017) - Published 25 April, 2017

ARTICLES

Structure, structural phase transitions, mechanical properties, defects

Inelastic x-ray investigation of the ferroelectric transition in SnTe

Christopher D. O'Neill, Dmitry A. Sokolov, Andreas Hermann, Alexei Bossak, Christopher Stock, and Andrew D. Huxley

Phys. Rev. B 95, 144101 (2017) - Published 3 April, 2017

Ground state structure of high-energy-density polymeric carbon monoxide

Kang Xia, Jian Sun, Chris J. Pickard, Dennis D. Klug, and Richard J. Needs

Phys. Rev. B 95, 144102 (2017) - Published 4 April, 2017

Low-temperature structural transition in the quasi-one-dimensional spin-12 compound Li2Cu2O(SO4)2

G. Rousse, J. Rodríguez-Carvajal, C. Giacobbe, M. Sun, O. Vaccarelli, and G. Radtke

Phys. Rev. B 95, 144103 (2017) - Published 5 April, 2017

Ionic and superionic phases in ammonia dihydrate NH3·2H2O under high pressure

Xue Jiang, Xue Wu, Zhaoyang Zheng, Yingying Huang, and Jijun Zhao

Phys. Rev. B 95, 144104 (2017) - Published 6 April, 2017

Ab initio simulations of the dynamic ion structure factor of warm dense lithium

B. B. L. Witte, M. Shihab, S. H. Glenzer, and R. Redmer

Phys. Rev. B 95, 144105 (2017) - Published 6 April, 2017

Pressure-induced transition to the collapsed tetragonal phase in BaCr2As2

P. G. Naumov, K. Filsinger, O. I. Barkalov, G. H. Fecher, S. A. Medvedev, and C. Felser

Phys. Rev. B 95, 144106 (2017) - Published 7 April, 2017

Mesoscale modeling of vacancy-mediated Si segregation near an edge dislocation in Ni under irradiation

Zebo Li and Dallas R. Trinkle

Phys. Rev. B 95, 144107 (2017) - Published 11 April, 2017

Elastic properties, thermal stability, and thermodynamic parameters of MoAlB

Sankalp Kota, Matthias Agne, Eugenio Zapata-Solvas, Olivier Dezellus, Diego Lopez, Bruno Gardiola, Miladin Radovic, and Michel W. Barsoum

Phys. Rev. B 95, 144108 (2017) - Published 13 April, 2017

Monolayer alkali and transition-metal monoxides: MgO, CaO, MnO, and NiO

F. Shayeganfar, K. S. Vasu, R. R. Nair, F. M. Peeters, and M. Neek-Amal

Phys. Rev. B 95, 144109 (2017) - Published 19 April, 2017

Representation of compounds for machine-learning prediction of physical properties

Atsuto Seko, Hiroyuki Hayashi, Keita Nakayama, Akira Takahashi, and Isao Tanaka

Phys. Rev. B 95, 144110 (2017) - Published 19 April, 2017

Shear-strain gradient induced polarization reversal in ferroelectric BaTiO3 thin films: A first-principles total-energy study

Guannan Li, Xiaokun Huang, Jingsan Hu, and Weiyi Zhang

Phys. Rev. B 95, 144111 (2017) - Published 19 April, 2017

Large negative thermal expansion in the cubic phase of CaMn7O12

K. Gautam, D. K. Shukla, S. Francoual, J. Bednarcik, J. R. L. Mardegan, H.-P. Liermann, R. Sankar, F. C. Chou, D. M. Phase, and J. Strempfer

Phys. Rev. B 95, 144112 (2017) - Published 24 April, 2017

Epicycle method for elasticity limit calculations

Axel van de Walle, Sara Kadkhodaei, Ruoshi Sun, and Qi-Jun Hong

Phys. Rev. B 95, 144113 (2017) - Published 25 April, 2017

Hugoniot and release measurements in diamond shocked up to 26 Mbar

M. C. Gregor, D. E. Fratanduono, C. A. McCoy, D. N. Polsin, A. Sorce, J. R. Rygg, G. W. Collins, T. Braun, P. M. Celliers, J. H. Eggert, D. D. Meyerhofer, and T. R. Boehly

Phys. Rev. B 95, 144114 (2017) - Published 26 April, 2017

Inhomogeneous, disordered, and partially ordered systems

Strain-dependent activation energy of shear transformation in metallic glasses

Bin Xu, Michael Falk, Jinfu Li, and Lingti Kong

Phys. Rev. B 95, 144201 (2017) - Published 12 April, 2017

Tunneling anomalous Hall effect in nanogranular CoFe-B-Al-O films near the metal-insulator transition

V. V. Rylkov, S. N. Nikolaev, K. Yu. Chernoglazov, V. A. Demin, A. V. Sitnikov, M. Yu. Presnyakov, A. L. Vasiliev, N. S. Perov, A. S. Vedeneev, Yu. E. Kalinin, V. V. Tugushev, and A. B. Granovsky

Phys. Rev. B 95, 144202 (2017) - Published 12 April, 2017

Barkhausen noise probe of the ferroelectric transition in the relaxor PbMg1/3Nb2/3O312%PbTiO3

Xinyang Zhang, Corbyn Mellinger, Eugene V. Colla, M. B. Weissman, and D. D. Viehland

Phys. Rev. B 95, 144203 (2017) - Published 18 April, 2017

Localization landscape theory of disorder in semiconductors. I. Theory and modeling

Marcel Filoche, Marco Piccardo, Yuh-Renn Wu, Chi-Kang Li, Claude Weisbuch, and Svitlana Mayboroda

Phys. Rev. B 95, 144204 (2017) - Published 18 April, 2017

Localization landscape theory of disorder in semiconductors. II. Urbach tails of disordered quantum well layers

Marco Piccardo, Chi-Kang Li, Yuh-Renn Wu, James S. Speck, Bastien Bonef, Robert M. Farrell, Marcel Filoche, Lucio Martinelli, Jacques Peretti, and Claude Weisbuch

Phys. Rev. B 95, 144205 (2017) - Published 18 April, 2017

Localization landscape theory of disorder in semiconductors. III. Application to carrier transport and recombination in light emitting diodes

Chi-Kang Li, Marco Piccardo, Li-Shuo Lu, Svitlana Mayboroda, Lucio Martinelli, Jacques Peretti, James S. Speck, Claude Weisbuch, Marcel Filoche, and Yuh-Renn Wu

Phys. Rev. B 95, 144206 (2017) - Published 18 April, 2017

Effect of interactions and disorder on the relaxation of two-level systems in amorphous solids

Ofek Asban, Ariel Amir, Yoseph Imry, and Moshe Schechter

Phys. Rev. B 95, 144207 (2017) - Published 20 April, 2017

Calculation of two-particle quantities in the typical medium dynamical cluster approximation

Y. Zhang, Y. F. Zhang, S. X. Yang, K.-M. Tam, N. S. Vidhyadhiraja, and M. Jarrell

Phys. Rev. B 95, 144208 (2017) - Published 21 April, 2017

Quantum and thermal melting of stripe forming systems with competing long-range interactions

Alejandro Mendoza-Coto, Daniel G. Barci, and Daniel A. Stariolo

Phys. Rev. B 95, 144209 (2017) - Published 26 April, 2017

Coupling between dynamic slowing down and chemical heterogeneity in a metallic undercooled liquid

N. Jakse and A. Pasturel

Phys. Rev. B 95, 144210 (2017) - Published 28 April, 2017

Correlating the properties of amorphous silicon with its flexibility volume

Zhao Fan, Jun Ding, Qing-Jie Li, and Evan Ma

Phys. Rev. B 95, 144211 (2017) - Published 28 April, 2017

Dynamics, dynamical systems, lattice effects

Theoretical simulations of oxygen K-edge resonant inelastic x-ray scattering of kaolinite

Emelie Ertan, Victor Kimberg, Faris Gel'mukhanov, Franz Hennies, Jan-Erik Rubensson, Thorsten Schmitt, Vladimir N. Strocov, Kejin Zhou, Marcella Iannuzzi, Alexander Föhlisch, Michael Odelius, and Annette Pietzsch

Phys. Rev. B 95, 144301 (2017) - Published 5 April, 2017

Ferroelectric phase transition and the lattice thermal conductivity of Pb1xGexTe alloys

Ronan M. Murphy, Éamonn D. Murray, Stephen Fahy, and Ivana Savić

Phys. Rev. B 95, 144302 (2017) - Published 6 April, 2017

Non-Hermitian acoustic metamaterials: Role of exceptional points in sound absorption

V. Achilleos, G. Theocharis, O. Richoux, and V. Pagneux

Phys. Rev. B 95, 144303 (2017) - Published 10 April, 2017

Quenching in Chern insulators with satellite Dirac points: The fate of edge states

Utso Bhattacharya, Joanna Hutchinson, and Amit Dutta

Phys. Rev. B 95, 144304 (2017) - Published 11 April, 2017

Tailoring the thermal conductivity in nanophononic metamaterials

Bing Li, K. T. Tan, and Johan Christensen

Phys. Rev. B 95, 144305 (2017) - Published 12 April, 2017

Nonequilibrium-induced enhancement of dynamical quantum coherence and entanglement of spin arrays

Zhedong Zhang, Hongchen Fu, and Jin Wang

Phys. Rev. B 95, 144306 (2017) - Published 12 April, 2017

Frequency comb generation using plasmonic resonances in a time-dependent graphene ribbon array

Galaad Altares Menendez and Bjorn Maes

Phys. Rev. B 95, 144307 (2017) - Published 13 April, 2017

Propagation and jamming dynamics in Heisenberg spin ladders

Carlo B. Krimphoff, Masudul Haque, and Andreas M. Läuchli

Phys. Rev. B 95, 144308 (2017) - Published 19 April, 2017

Thermal conductivity decomposition in two-dimensional materials: Application to graphene

Zheyong Fan, Luiz Felipe C. Pereira, Petri Hirvonen, Mikko M. Ervasti, Ken R. Elder, Davide Donadio, Tapio Ala-Nissila, and Ari Harju

Phys. Rev. B 95, 144309 (2017) - Published 19 April, 2017

Effects of grain boundaries and defects on anisotropic magnon transport in textured Sr14Cu24O41

Xi Chen, Karalee Jarvis, Sean Sullivan, Yutao Li, Jianshi Zhou, and Li Shi

Phys. Rev. B 95, 144310 (2017) - Published 27 April, 2017

The strong spin-spin exchange interaction in some low-dimensional magnetic materials can give rise to a high group velocity and thermal conductivity contribution from magnons, which are energy quanta of collective spin excitations. Examples are the incommensurate layered compounds (Sr,Ca,La)14Cu24O41, with strong antiferromagnetic interaction along the ladders. The effects of grain boundaries and defects on quasi-one-dimensional magnon transport in these compounds are not well understood. Here, the authors report the microstructures and anisotropic thermal transport properties of textured Sr14Cu24O41. TEM clearly reveals nanolayered grains and the presence of dislocations and planar defects. The thermal conductivity contribution and mean free paths of magnons in the textured samples are evaluated with the use of a kinetic model for one-dimensional magnon transport, and found to be suppressed significantly compared to single crystals at low temperatures. The experimental results can be explained by a one-dimensional magnon-defect scattering model, provided that the magnon–grain boundary scattering mean free path in the anisotropic magnetic structure is smaller than the average length of these nanolayers along the c axis. The finding suggests low transmission coefficients for energy-carrying magnons across grain boundaries.

Generating surface states in a Weyl semimetal by applying electromagnetic radiation

Oindrila Deb and Diptiman Sen

Phys. Rev. B 95, 144311 (2017) - Published 28 April, 2017

Magnetism

Effects of spatially engineered Dzyaloshinskii-Moriya interaction in ferromagnetic films

Jeroen Mulkers, Bartel Van Waeyenberge, and Milorad V. Milošević

Phys. Rev. B 95, 144401 (2017) - Published 3 April, 2017

Spin superfluid Josephson quantum devices

So Takei, Yaroslav Tserkovnyak, and Masoud Mohseni

Phys. Rev. B 95, 144402 (2017) - Published 4 April, 2017

Spin Hall phenomena are a collection of relativistic spin-orbit coupling effects that permit control and detection of magnetization dynamics in magnetic materials with electrical currents. In spintronics, they have been studied extensively in bilayer structures consisting of a magnetically ordered material interfaced by a current-carrying paramagnetic metal with strong spin-orbit coupling. In this work, the authors propose the magnetic phase qubit, the macroscopic quantum spintronic device that can be built from such bilayers and that permits full electrical control and readout via spin Hall phenomena. The device is an example of a macroscopic qubit that can be constructed from solid-state materials and so should offer the same advantages as the superconducting qubits of strong inter-qubit coupling and scalability. An estimate of the relevant physical parameters based on current spintronic technology gives a qubit operational temperature that is more than an order of magnitude higher than for existing superconducting qubits, thus opening the possibility of macroscopic quantum information processing at temperatures above the dilution refrigerator range. The authors also show that a coupled array of these qubits can realize a quantum annealer, which could be used to solve certain hard optimization problems and machine learning tasks.

Field-temperature phase diagram of magnetic bubbles spanning charge/orbital ordered and metallic phases in La1xSrxMnO3 (x=0.125)

A. Kotani, H. Nakajima, K. Harada, Y. Ishii, and S. Mori

Phys. Rev. B 95, 144403 (2017) - Published 4 April, 2017

Properties of spin-12 triangular-lattice antiferromagnets CuY2Ge2O8 and CuLa2Ge2O8

Hwanbeom Cho, Marie Kratochvílová, Hasung Sim, Ki-Young Choi, Choong Hyun Kim, Carley Paulsen, Maxim Avdeev, Darren C. Peets, Younghun Jo, Sanghyun Lee, Yukio Noda, Michael J. Lawler, and Je-Geun Park

Phys. Rev. B 95, 144404 (2017) - Published 5 April, 2017

Quantifying angular dependence of spin-orbit torques in Ta/CoFeB/MgO trilayers with perpendicular magnetic anisotropy

Yunpeng Chen, Halise Celik, Tao Wang, Harsha Kannan, Ilya N. Krivorotov, and John Q. Xiao

Phys. Rev. B 95, 144405 (2017) - Published 7 April, 2017

Heat capacity evidence for proximity to the Kitaev quantum spin liquid in A2 IrO3 (A=Na, Li)

Kavita Mehlawat, A. Thamizhavel, and Yogesh Singh

Phys. Rev. B 95, 144406 (2017) - Published 7 April, 2017

Competing spin density wave, collinear, and helical magnetism in Fe1+xTe

C. Stock, E. E. Rodriguez, P. Bourges, R. A. Ewings, H. Cao, S. Chi, J. A. Rodriguez-Rivera, and M. A. Green

Phys. Rev. B 95, 144407 (2017) - Published 7 April, 2017

Electrically driven Bose-Einstein condensation of magnons in antiferromagnets

Eirik Løhaugen Fjærbu, Niklas Rohling, and Arne Brataas

Phys. Rev. B 95, 144408 (2017) - Published 10 April, 2017

Reentrant superspin glass state and magnetization steps in the oxyborate Co2AlBO5

Jitender Kumar, Soumendra Nath Panja, Deepak John Mukkattukavil, Arpan Bhattacharyya, A. K. Nigam, and Sunil Nair

Phys. Rev. B 95, 144409 (2017) - Published 10 April, 2017

Interplay of dilution and magnetic field in the nearest-neighbor spin-ice model on the pyrochlore lattice

Alexey Peretyatko, Konstantin Nefedev, and Yutaka Okabe

Phys. Rev. B 95, 144410 (2017) - Published 11 April, 2017

Counter-rotating standing spin waves: A magneto-optical illusion

S. Shihab, L. Thevenard, A. Lemaître, and C. Gourdon

Phys. Rev. B 95, 144411 (2017) - Published 12 April, 2017

In ferromagnetic layers, spin-wave modes can be excited by a laser pulse launching the magnetization out of equilibrium and into precession. The trajectory of the magnetization vector can be fully reconstructed using different magneto-optical effects, generally admitted to give a faithful picture of the dynamics. The authors show that this is not always the case and that magneto-optical effects can indeed be deceiving. For this, they study the case of a weakly absorbing ferromagnet, the semiconductor GaMnAs, in which perpendicular standing spin waves are excited by a laser pulse. Quite counterintuitively, the optical detection shows the first two excited modes to be of opposite chirality, whereas theory tells us the spin waves actually rotate in the same direction. The paper demonstrates that this unexpected and surprising effect is a pure optical illusion. It can perfectly be explained by taking into account absorption and optical phase shift inside the layer, the latter being particularly strong in weakly absorbing layers. These results provide a correct identification of spin-wave modes, enabling a trustworthy estimation of their respective weight as well as an unambiguous determination of the spin stiffness parameter.

Synchronization of spin torque nano-oscillators

James Turtle, Pietro-Luciano Buono, Antonio Palacios, Christine Dabrowski, Visarath In, and Patrick Longhini

Phys. Rev. B 95, 144412 (2017) - Published 12 April, 2017

Coupled spin-12 ladders as microscopic models for non-Abelian chiral spin liquids

Po-Hao Huang, Jyong-Hao Chen, Adrian E. Feiguin, Claudio Chamon, and Christopher Mudry

Phys. Rev. B 95, 144413 (2017) - Published 12 April, 2017

Single-ion properties of the Seff = 12 XY antiferromagnetic pyrochlores NaACo2F7 (A=Ca2+, Sr2+)

K. A. Ross, J. M. Brown, R. J. Cava, J. W. Krizan, S. E. Nagler, J. A. Rodriguez-Rivera, and M. B. Stone

Phys. Rev. B 95, 144414 (2017) - Published 13 April, 2017

Quantum effects in magnetic materials are prevalent when the magnetic ions support spin-½ moments, as in Cu2+-based materials. Strong quantum effects can also be achieved when the large angular momentum states are reduced to an effective spin-½ subspace (Seff=½) by the combined effect of spin-orbit coupling and the crystal electric field. A consequence of this is the introduction of anisotropy to the g tensor and the effective exchange interactions. Such anisotropic Seff=½ models have recently been applied successfully to rare-earth based frustrated pyrochlore materials, where they are found to lead to particularly rich phenomenology for XY-like g tensors. Here, it is shown that a similar quantum model should apply to the recently discovered “high temperature” Co2+ pyrochlores, NaCaCo2F7 and NaSrCo2F7, based on a fit to their single ion levels as measured via inelastic neutron scattering. The effect of the intrinsic crystalline disorder on the anisotropy of the Seff=½ moments in these materials is also estimated.

Competing phases in spin ladders with ring exchange and frustration

Alexandros Metavitsiadis and Sebastian Eggert

Phys. Rev. B 95, 144415 (2017) - Published 13 April, 2017

Characterization of switching field distributions in Ising-like magnetic arrays

Robert D. Fraleigh, Susan Kempinger, Paul E. Lammert, Sheng Zhang, Vincent H. Crespi, Peter Schiffer, and Nitin Samarth

Phys. Rev. B 95, 144416 (2017) - Published 13 April, 2017

Anisotropy constant and exchange coupling strength of perpendicularly magnetized CoFeB/Pd multilayers and exchange springs

A. F. Franco, C. Gonzalez-Fuentes, J. Åkerman, and C. Garcia

Phys. Rev. B 95, 144417 (2017) - Published 14 April, 2017

Phase-separated magnetic ground state in Mn3Ga0.45Sn0.55C

E. T. Dias, K. R. Priolkar, A. K. Nigam, R. Singh, A. Das, and G. Aquilanti

Phys. Rev. B 95, 144418 (2017) - Published 14 April, 2017

Ising-like antiferromagnetism on the octahedral sublattice of a cobalt-containing garnet and the potential for quantum criticality

Abbey J. Neer, JoAnna Milam-Guerrero, Justin E. So, Brent C. Melot, Kate A. Ross, Zeric Hulvey, Craig M. Brown, Alexey A. Sokol, and David O. Scanlon

Phys. Rev. B 95, 144419 (2017) - Published 14 April, 2017

Magnon-polaron transport in magnetic insulators

Benedetta Flebus, Ka Shen, Takashi Kikkawa, Ken-ichi Uchida, Zhiyong Qiu, Eiji Saitoh, Rembert A. Duine, and Gerrit E. W. Bauer

Phys. Rev. B 95, 144420 (2017) - Published 14 April, 2017

Antiferromagnetism in the van der Waals layered spin-lozenge semiconductor CrTe3

Michael A. McGuire, V. Ovidiu Garlea, Santosh KC, Valentino R. Cooper, Jiaqiang Yan, Huibo Cao, and Brian C. Sales

Phys. Rev. B 95, 144421 (2017) - Published 14 April, 2017

Magnetization precession induced by picosecond acoustic pulses in a freestanding film acting as an acoustic cavity

Ji-Wan Kim and Jean-Yves Bigot

Phys. Rev. B 95, 144422 (2017) - Published 17 April, 2017

Low-energy magnetoelectric control of domain states in exchange-coupled heterostructures

Muftah Al-Mahdawi, Satya Prakash Pati, Yohei Shiokawa, Shujun Ye, Tomohiro Nozaki, and Masashi Sahashi

Phys. Rev. B 95, 144423 (2017) - Published 17 April, 2017

Contribution from optically excited many-electron states to the superexchange interaction in Mott-Hubbard insulators

Vladimir A. Gavrichkov, Semen I. Polukeev, and Sergey G. Ovchinnikov

Phys. Rev. B 95, 144424 (2017) - Published 17 April, 2017

Quantum spin liquid with seven elementary particles

Haoyu Wang, Hitesh J. Changlani, Yuan Wan, and Oleg Tchernyshyov

Phys. Rev. B 95, 144425 (2017) - Published 18 April, 2017

Tuning the competing phases of bilayer ruthenate Ca3Ru2O7 via dilute Mn impurities and magnetic field

M. Zhu, J. Peng, W. Tian, T. Hong, Z. Q. Mao, and X. Ke

Phys. Rev. B 95, 144426 (2017) - Published 21 April, 2017

Kitaev-Heisenberg model in a magnetic field: Order-by-disorder and commensurate-incommensurate transitions

Gia-Wei Chern, Yuriy Sizyuk, Craig Price, and Natalia B. Perkins

Phys. Rev. B 95, 144427 (2017) - Published 21 April, 2017

Bilayer linearized tensor renormalization group approach for thermal tensor networks

Yong-Liang Dong, Lei Chen, Yun-Jing Liu, and Wei Li

Phys. Rev. B 95, 144428 (2017) - Published 24 April, 2017

Magnetism of the antiferromagnetic spin-32 dimer compound CrVMoO7 having an antiferromagnetically ordered state

Masashi Hase, Yuta Ebukuro, Haruhiko Kuroe, Masashige Matsumoto, Akira Matsuo, Koichi Kindo, James R. Hester, Taku J. Sato, and Hiroki Yamazaki

Phys. Rev. B 95, 144429 (2017) - Published 24 April, 2017

Systematic study of the physical origin of ferromagnetism in CeO2δ nanoparticles

A. N. Ribeiro and N. S. Ferreira

Phys. Rev. B 95, 144430 (2017) - Published 27 April, 2017

Direct observation of magnetic domains by Kerr microscopy in a Ni-Mn-Ga magnetic shape-memory alloy

O. Perevertov, O. Heczko, and R. Schäfer

Phys. Rev. B 95, 144431 (2017) - Published 27 April, 2017

Spin superfluidity and spin waves in YIG films

E. B. Sonin

Phys. Rev. B 95, 144432 (2017) - Published 27 April, 2017

Recently, it was suggested that metastable spin supercurrents (spin superfluidity) are possible in the magnon condensate observed in yttrium iron garnet (YIG) magnetic films under strong magnon pumping. In YIG, magnetic anisotropy is rather weak, and this material can be treated as an isotropic ferromagnet. Its order-parameter space is a sphere of radius equal to the spontaneous magnetization M. A current state maps on the equatorial circumference on the sphere, and topology of the sphere allows us to continuously transform the equatorial circumference to the point. This rules out metastable current states. Only easy-plane anisotropy reducing the order-parameter space from the sphere to the equatorial circumference makes current states topologically stable. However, by pumping magnons to the isotropic ferromagnet in a magnetic field, it is possible to support a strongly nonequilibrium state with fixed average Mz. This confines the precessing spin to an “easy plane” of dynamical rather than topological origin and makes metastable spin currents possible. But final judgment requires evaluation of the Landau superfluidity criterion as done in the present work. The conclusion is that spin superfluidity in YIG films is possible in principle, although the recently published claim of its observation is not justified.

Universality of the helimagnetic transition in cubic chiral magnets: Small angle neutron scattering and neutron spin echo spectroscopy studies of FeCoSi

L. J. Bannenberg, K. Kakurai, P. Falus, E. Lelièvre-Berna, R. Dalgliesh, C. D. Dewhurst, F. Qian, Y. Onose, Y. Endoh, Y. Tokura, and C. Pappas

Phys. Rev. B 95, 144433 (2017) - Published 28 April, 2017

Chiral magnetism plays an increasingly important role in condensed matter investigations driven by the discovery of exotic spin textures, such as the topologically protected chiral skyrmions that can form a lattice under magnetic fields. The nature and universality of the phase diagram in cubic chiral magnets has been the subject of numerous experimental and theoretical investigations, including the transition to the helimagnetic state. In MnSi, the archetypal system in this family, this transition is of first order and involves a precursor phase, where strong chiral fluctuating correlations build up. This work presents an experimental investigation of the structural and dynamical aspects of the phase transition in Fe1-xCoxSi, a system that belongs to the same family as MnSi but with the additional possibility to tune important physical interactions and parameters through variation of the Fe and Co concentration. In this system, the combination of small-angle neutron scattering and neutron spin echo spectroscopy uncovers that the scenario of the transition is qualitatively very different from that in MnSi. This goes beyond what can be expected from a comparison of the relevant length scales and thus challenges the validity of a universal approach to the helimagnetic transition in cubic chiral magnets.

Superfluidity and superconductivity

Phase diagram of bosons in a two-dimensional optical lattice with infinite-range cavity-mediated interactions

T. Flottat, L. de Forges de Parny, F. Hébert, V. G. Rousseau, and G. G. Batrouni

Phys. Rev. B 95, 144501 (2017) - Published 3 April, 2017

Magnetic impurity effects on the superconductivity of noncentrosymmetric LaNiC2: Ce substitution for La

Susumu Katano, Kohei Shibata, Kotaro Nakashima, and Yohei Matsubara

Phys. Rev. B 95, 144502 (2017) - Published 3 April, 2017

Disorder-enhanced topological protection and universal quantum criticality in a spin-32 topological superconductor

Sayed Ali Akbar Ghorashi, Seth Davis, and Matthew S. Foster

Phys. Rev. B 95, 144503 (2017) - Published 3 April, 2017

Magnetic gates and guides for superconducting vortices

V. K. Vlasko-Vlasov, F. Colauto, A. I. Buzdin, D. Rosenmann, T. Benseman, and W.-K. Kwok

Phys. Rev. B 95, 144504 (2017) - Published 4 April, 2017

Evidence for topological behavior in superconducting CuxZrTe2y

A. J. S. Machado, N. P. Baptista, B. S. de Lima, N. Chaia, T. W. Grant, L. E. Corrêa, S. T. Renosto, A. C. Scaramussa, R. F. Jardim, M. S. Torikachvili, J. Albino Aguiar, O. C. Cigarroa, L. T. F. Eleno, and Z. Fisk

Phys. Rev. B 95, 144505 (2017) - Published 4 April, 2017

Staggered quantum walks with superconducting microwave resonators

J. Khatibi Moqadam, M. C. de Oliveira, and R. Portugal

Phys. Rev. B 95, 144506 (2017) - Published 5 April, 2017

Possible superconductivity in the electron-doped chromium pnictide LaOCrAs

Wan-Sheng Wang, Miao Gao, Yang Yang, Yuan-Yuan Xiang, and Qiang-Hua Wang

Phys. Rev. B 95, 144507 (2017) - Published 17 April, 2017

Unconventional superconductivity and anomalous response in hole-doped transition metal dichalcogenides

Evan Sosenko, Junhua Zhang, and Vivek Aji

Phys. Rev. B 95, 144508 (2017) - Published 18 April, 2017

Bulklike excitations in nanoconfined liquid helium

M. S. Bryan, T. R. Prisk, T. E. Sherline, S. O. Diallo, and P. E. Sokol

Phys. Rev. B 95, 144509 (2017) - Published 20 April, 2017

Large-scale modulation in the superconducting properties of thin films due to domains in the SrTiO3 substrate

Shai Wissberg and Beena Kalisky

Phys. Rev. B 95, 144510 (2017) - Published 20 April, 2017

Nematicity at the Hund's metal crossover in iron superconductors

L. Fanfarillo, G. Giovannetti, M. Capone, and E. Bascones

Phys. Rev. B 95, 144511 (2017) - Published 24 April, 2017

Spectral representation of the heat current in a driven Josephson junction

P. Virtanen, P. Solinas, and F. Giazotto

Phys. Rev. B 95, 144512 (2017) - Published 24 April, 2017

Experimental evidence for importance of Hund's exchange interaction for incoherence of charge carriers in iron-based superconductors

J. Fink, E. D. L. Rienks, S. Thirupathaiah, J. Nayak, A. van Roekeghem, S. Biermann, T. Wolf, P. Adelmann, H. S. Jeevan, P. Gegenwart, S. Wurmehl, C. Felser, and B. Büchner

Phys. Rev. B 95, 144513 (2017) - Published 25 April, 2017

Anisotropic Andreev reflection and Josephson effect in ballistic phosphorene

Jacob Linder and Takehito Yokoyama

Phys. Rev. B 95, 144515 (2017) - Published 26 April, 2017

Optical properties of Bogoliubov quasiparticles

E. Schachinger and J. P. Carbotte

Phys. Rev. B 95, 144516 (2017) - Published 27 April, 2017

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