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Articles 1 - 16 of 16
Full-Text Articles in Physical Sciences and Mathematics
Ferroelectric-Driven Tunable Magnetism In Ultrathin Platinum Films, Qilong Sun, Farzad Mahfouzi, Julian P. Velev, Evgeny Y. Tsymbal, Nicholas Kioussis
Ferroelectric-Driven Tunable Magnetism In Ultrathin Platinum Films, Qilong Sun, Farzad Mahfouzi, Julian P. Velev, Evgeny Y. Tsymbal, Nicholas Kioussis
Department of Physics and Astronomy: Faculty Publications
Electric control of magnetism in magnetoelectric (ME) multiferroics is expected to have a significant impact on a wide range of technological applications. Here, we predict the modulation of magnetism in ultrathin platinum films due to the ferroelectric polarization of the BaTiO3 substrate, which along with biaxial strain changes the density of states at the Fermi energy. We demonstrate that both the magnitude and direction of the magnetization depend strongly on the polarization direction and/or strain. This leads to an unprecedented ME effect involving a giant change of magnetocrystalline anisotropy under polarization switching due to the large spin-orbit coupling of …
Discovering Rare-Earth-Free Magnetic Materials Through The Development Of A Database, Masahiro Sakurai, Renhai Wang, Timothy Liao, Chao Zhang, Huaijun Sun, Yang Sun, Haidi Wang, Xin Zhao, Songyou Wang, Balamurugan Balasubramanian, Xiaoshan S. Xu, David J. Sellmyer, Vladimir Antropov, Jianhua Zhang, Cai-Zhuang Wang, Kai-Ming Ho, James R. Chelikowsky
Discovering Rare-Earth-Free Magnetic Materials Through The Development Of A Database, Masahiro Sakurai, Renhai Wang, Timothy Liao, Chao Zhang, Huaijun Sun, Yang Sun, Haidi Wang, Xin Zhao, Songyou Wang, Balamurugan Balasubramanian, Xiaoshan S. Xu, David J. Sellmyer, Vladimir Antropov, Jianhua Zhang, Cai-Zhuang Wang, Kai-Ming Ho, James R. Chelikowsky
Department of Physics and Astronomy: Faculty Publications
We develop an open-access database that provides a large array of datasets specialized for magnetic compounds as well as magnetic clusters. Our focus is on rare-earth-free magnets. Available datasets include (i) crystallography, (ii) thermodynamic properties, such as the formation energy, and (iii) magnetic properties that are essential for magnetic-material design. Our database features a large number of stable and metastable structures discovered through our adaptive genetic algorithm (AGA) searches. Many of these AGA structures have better magnetic properties when compared to those of the existing rare-earth-free magnets and the theoretical structures in other databases. Our database places particular emphasis on …
Nonlocal Complex Potential Theory Of Dissociative Electron Attachment: Inclusion Of Two Vibrational Modes, H. B. Ambalampitiya, Ilya I. Fabrikant
Nonlocal Complex Potential Theory Of Dissociative Electron Attachment: Inclusion Of Two Vibrational Modes, H. B. Ambalampitiya, Ilya I. Fabrikant
Department of Physics and Astronomy: Faculty Publications
The process of dissociative electron attachment (DEA) to molecules with several vibrational degrees of freedom is usually treated in the approximation of the local potential for the description of the nuclear motion. We develop the nonlocal complex potential theory to treat the dissociation dynamics when there is more than one vibrational mode in the neutral molecule. We demonstrate the application of the multimode nonlocal theory to a generic molecule of the type CY3X, where Y denotes the H or F atom and X denotes the halogen atom, with the inclusion of symmetric C–X stretch and CY3 deform …
Electrical Detection Of Ferroelectriclike Metals Through The Nonlinear Hall Effect, Rui-Chun Xiao, Ding-Fu Shao, Wenjuan Huang, Hua Jiang
Electrical Detection Of Ferroelectriclike Metals Through The Nonlinear Hall Effect, Rui-Chun Xiao, Ding-Fu Shao, Wenjuan Huang, Hua Jiang
Department of Physics and Astronomy: Faculty Publications
Ferroelectriclike metals are a relatively rare class of materials that have ferroelectriclike distortion and metallic conductivity. LiOsO3 is the first demonstrated and the most investigated ferroelectriclike metal. The presence of free carriers makes them difficult to be studied by traditional ferroelectric techniques. In this paper, using symmetry analysis and first-principles calculations, we demonstrate that the ferroelectriclike transition of LiOsO3 can be probed by a kind of electrical transport method based on nonlinear Hall effect. The Berry curvature dipole exists in the ferroelectriclike phase and it can lead to a measurable nonlinear Hall conductance with a conventional experimental setup. …
Lepton Flavor Violation And Dilepton Tails At The Lhc, Andrei Angelescu, Darius A. Faroughy, Olcyr Sumensari
Lepton Flavor Violation And Dilepton Tails At The Lhc, Andrei Angelescu, Darius A. Faroughy, Olcyr Sumensari
Department of Physics and Astronomy: Faculty Publications
Starting from a general effective Lagrangian for lepton flavor violation (LFV) in quark-lepton transitions, we derive constraints on the effective coefficients from the high-mass tails of the dilepton processes pp → ℓkℓl (with k ≠ l). The current (projected) limits derived in this paper from LHC data with 36 fb−1 (3 ab−1) can be applied to generic new physics scenarios, including the ones with scalar, vector and tensor effective operators. For purely left-handed operators, we explicitly compare these LHC constraints with the ones derived from flavor-physics observables, illustrating the complementarity of these different probes. …
Perspective: Ferromagnetic Liquids, Robert Streubel, Xubo Liu, Xuefei Wu, Thomas P. Russell
Perspective: Ferromagnetic Liquids, Robert Streubel, Xubo Liu, Xuefei Wu, Thomas P. Russell
Department of Physics and Astronomy: Faculty Publications
Mechanical jamming of nanoparticles at liquid–liquid interfaces has evolved into a versatile approach to structure liquids with solid-state properties. Ferromagnetic liquids obtain their physical and magnetic properties, including a remanent magnetization that distinguishes them from ferrofluids, from the jamming of magnetic nanoparticles assembled at the interface between two distinct liquids to minimize surface tension. This perspective provides an overview of recent progress and discusses future directions, challenges and potential applications of jamming magnetic nanoparticles with regard to 3D nano-magnetism. We address the formation and characterization of curved magnetic geometries, and spin frustration between dipole-coupled nanostructures, and advance our understanding of …
Generalized Magnetoelectronic Circuit Theory And Spin Relaxation At Interfaces In Magnetic Multilayers, G. G. Baez Flores, Alexey Kovalev, Mark Van Schilfgaarde, K. D. Belashchenko
Generalized Magnetoelectronic Circuit Theory And Spin Relaxation At Interfaces In Magnetic Multilayers, G. G. Baez Flores, Alexey Kovalev, Mark Van Schilfgaarde, K. D. Belashchenko
Department of Physics and Astronomy: Faculty Publications
Spin transport at metallic interfaces is an essential ingredient of various spintronic device concepts, such as giant magnetoresistance, spin-transfer torque, and spin pumping. Spin-orbit coupling plays an important role in many such devices. In particular, spin current is partially absorbed at the interface due to spin-orbit coupling. We develop a general magnetoelectronic circuit theory and generalize the concept of spin-mixing conductance, accounting for various mechanisms responsible for spin-flip scattering. For the special case when exchange interactions dominate, we give a simple expression for the spin-mixing conductance in terms of the contributions responsible for spin relaxation (i.e., spin memory loss), spin …
Semiclassical Theory Of Laser-Assisted Radiative Recombination, Ilya I. Fabrikant, H. B. Ambalampitiya
Semiclassical Theory Of Laser-Assisted Radiative Recombination, Ilya I. Fabrikant, H. B. Ambalampitiya
Department of Physics and Astronomy: Faculty Publications
We study the process of laser-assisted radiative recombination of an electron with a proton by using a semiclassical approach involving calculation of classical trajectories in combined laser and Coulomb fields. Due to chaotic scattering in the combined fields, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits chaotic behavior and fractal structures. We obtain a strong enhancement of the recombination cross section as compared to the laser-free case due to the Coulomb focusing effect. For sufficiently low incident electron velocities the cross section becomes infinite, and we limit it by …
Spin-Torque Switching Of Noncollinear Antiferromagnetic Antiperovskites, Gautam Gurung, Ding-Fu Shao, Evgeny Y. Tsymbal
Spin-Torque Switching Of Noncollinear Antiferromagnetic Antiperovskites, Gautam Gurung, Ding-Fu Shao, Evgeny Y. Tsymbal
Department of Physics and Astronomy: Faculty Publications
Antiferromagnetic (AFM) spintronics exploits the Néel vector as a state variable for novel electronic devices. Recent studies have demonstrated that the Néel vector can be switched by a spin-orbit torque. These studies however are largely limited to collinear antiferromagnets of proper magnetic space-group symmetry. There is, however, a large group of high-temperature noncollinear antiferromagnets, which are suitable for such switching. Here, we predict that spin torque can be efficiently used to switch a noncollinear AFM order in antiperovskite materials. Based on first-principles calculations and atomistic spin-dynamics modeling, we show that in antiperovskites ANMn3 (A = Ga, Ni, etc.) with …
Strain-Driven Disproportionation At A Correlated Oxide Metal-Insulator Transition, T. H. Kim, Tula R. Paudel, R. J. Green, K. Song, H.-S. Lee, S.-Y. Choi, J. Irwin, B. Noesges, L. J. Brillson, M. S. Rzchowski, G. A. Sawatzky, Evgeny Y. Tsymbal, C. B. Eom
Strain-Driven Disproportionation At A Correlated Oxide Metal-Insulator Transition, T. H. Kim, Tula R. Paudel, R. J. Green, K. Song, H.-S. Lee, S.-Y. Choi, J. Irwin, B. Noesges, L. J. Brillson, M. S. Rzchowski, G. A. Sawatzky, Evgeny Y. Tsymbal, C. B. Eom
Department of Physics and Astronomy: Faculty Publications
Metal-to-insulator phase transitions in complex oxide thin films are exciting phenomena which may be useful for device applications, but in many cases the physical mechanism responsible for the transition is not fully understood. Here we demonstrate that epitaxial strain generates local disproportionation of the NiO6 octahedra, driven through changes in the oxygen stoichiometry, and that this directly modifies the metal-to-insulator phase transition in epitaxial (001) NdNiO3 thin films. Theoretically, we predict that the Ni-O-Ni bond angle decreases, while octahedral tilt and local disproportionation of the NiO6 octahedra increases resulting in a small band gap in an otherwise …
Nonlinear Anomalous Hall Effect For Néel Vector Detection, Ding-Fu Shao, Shu-Hui Zhang, Gautam Gurung, Wen Yang, Evgeny Y. Tsymbal
Nonlinear Anomalous Hall Effect For Néel Vector Detection, Ding-Fu Shao, Shu-Hui Zhang, Gautam Gurung, Wen Yang, Evgeny Y. Tsymbal
Department of Physics and Astronomy: Faculty Publications
Antiferromagnetic (AFM) spintronics exploits the Néel vector as a state variable for novel spintronic devices. Recent studies have shown that the fieldlike and antidamping spin-orbit torques (SOTs) can be used to switch the Néel vector in antiferromagnets with proper symmetries. However, the precise detection of the Néel vector remains a challenging problem. In this Letter, we predict that the nonlinear anomalous Hall effect (AHE) can be used to detect the Néel vector in most compensated antiferromagnets supporting the antidamping SOT. We show that the magnetic crystal group symmetry of these antiferromagnets combined with spin-orbit coupling produce a sizable Berry curvature …
Perpendicular Magnetic Anisotropy In Conducting Nico2O4 Films From Spin-Lattice Coupling, Corbyn Mellinger, Jace Waybright, Xiaozhe Zhang, Caleb Schmidt, Xiaoshan S. Xu
Perpendicular Magnetic Anisotropy In Conducting Nico2O4 Films From Spin-Lattice Coupling, Corbyn Mellinger, Jace Waybright, Xiaozhe Zhang, Caleb Schmidt, Xiaoshan S. Xu
Department of Physics and Astronomy: Faculty Publications
High perpendicular magnetic anisotropy (PMA), a property needed for nanoscale spintronic applications, is rare in oxide conductors. We report the observation of a PMA up to 0.23 MJ/m3 in modestly strained (–0.3%) epitaxial NiCo2O4 films which are room-temperature ferrimagnetic conductors. Spin-lattice coupling manifested as magnetoelastic effect was found as the origin of the PMA. The in-plane x2-y2 states of Co on tetrahedral sites play crucial role in the magnetic anisotropy and spin-lattice coupling with an energy scale of 1 meV/f.u. The elucidation of the microscopic origin paves a way for engineering oxide conductors …
Magnon Landau Levels And Spin Responses In Antiferromagnets, Bo Li, Alexey Kovalev
Magnon Landau Levels And Spin Responses In Antiferromagnets, Bo Li, Alexey Kovalev
Department of Physics and Astronomy: Faculty Publications
We study gauge fields produced by gradients of the Dzyaloshinskii-Moriya interaction and propose a model of an AFM topological insulator of magnons. In the long wavelength limit, the Landau levels induced by the inhomogeneous Dzyaloshinskii-Moriya interaction exhibit relativistic physics described by the Klein-Gordon equation. The spin Nernst response due to the formation of magnonic Landau levels is compared to similar topological responses in skyrmion and vortex-antivortex crystal phases of AFM insulators. Our studies show that AFM insulators exhibit rich physics associated with topological magnon excitations.
Magnonic Analog Of The Edelstein Effect In Antiferromagnetic Insulators, Bo Li, Alexander Mook, Aldo Raeliarijaona, Alexey Kovalev
Magnonic Analog Of The Edelstein Effect In Antiferromagnetic Insulators, Bo Li, Alexander Mook, Aldo Raeliarijaona, Alexey Kovalev
Department of Physics and Astronomy: Faculty Publications
We investigate the nonequilibrium spin polarization due to a temperature gradient in antiferromagnetic insulators, which is the magnonic analog of the inverse spin-galvanic effect of electrons. We derive a linear-response theory of a temperature-gradient-induced spin polarization for collinear and noncollinear antiferromagnets, which comprises both extrinsic and intrinsic contributions. We apply our theory to several noncentrosymmetric antiferromagnetic insulators, i.e., to a one-dimensional antiferromagnetic spin chain, a single layer of kagome noncollinear antiferromagnet,e.g.,KFe3(OH)6(SO4)2,and a noncollinear breathing pyrochlore antiferromagnet, e.g., LiGaCr4O8. The shapes of our numerically evaluated response tensors agree with those implied by the magnetic symmetry. Assuming a realistic temperature gradient of …
Intrinsic Spin Nernst Effect Of Magnons In A Noncollinear Antiferromagnet, Bo Li, Shane Sandhoefner, Alexey Kovalev
Intrinsic Spin Nernst Effect Of Magnons In A Noncollinear Antiferromagnet, Bo Li, Shane Sandhoefner, Alexey Kovalev
Department of Physics and Astronomy: Faculty Publications
We investigate the intrinsic magnon spin current in a noncollinear antiferromagnetic insulator. We introduce a definition of the magnon spin current in a noncollinear antiferromagnet and find that it is in general nonconserved, but for certain symmetries and spin polarizations the averaged effect of nonconserving terms can vanish. We formulate a general linear response theory for magnons in noncollinear antiferromagnets subject to a temperature gradient and analyze the effect of symmetries on the response tensor. We apply this theory to single-layer potassium iron jarosite KFe3(OH)6(SO4)2 and predict a measurable spin current response.
Interfacial Contributions To Spin-Orbit Torque And Magnetoresistance In Ferromagnet/Heavy-Metal Bilayers, Kirill Belashchenko, Alexey Kovalev, Mark Van Schilfgaarde
Interfacial Contributions To Spin-Orbit Torque And Magnetoresistance In Ferromagnet/Heavy-Metal Bilayers, Kirill Belashchenko, Alexey Kovalev, Mark Van Schilfgaarde
Department of Physics and Astronomy: Faculty Publications
The thickness dependence of spin-orbit torque and magnetoresistance in ferromagnet/heavy-metal bilayers is studied using the first-principles nonequilibrium Green’s function formalism combined with the Anderson disorder model. A systematic expansion in orthogonal vector spherical harmonics is used for the angular dependence of the torque. The dampinglike torque in Co/Pt and Co/Au bilayers can be described as a sum of the spin-Hall contribution, which increases with thickness in agreement with the spin-diffusion model, and a comparable interfacial contribution. The magnetoconductance in the plane perpendicular to the current in Co/Pt bilayers is of the order of a conductance quantum per interfacial atom, exceeding …