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Michael Hinczewski - One of the best experts on this subject based on the ideXlab platform.
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excitation spectrum gap and spin wave velocity of xxz heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic XXZ spin-1/2 Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated thoughout the entire temperature and anisotropy ranges in both ferromagnetic and Antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the Antiferromagnetic spin-liquid spin-wave velocity and the Isinglike ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction s_i^x s_j^x + s_i^y s_j^y induces an Antiferromagnetic correlation in the out-of-plane s_i^z component, at higher temperatures in the Antiferromagnetic XXZ chain, dominantly at low temperatures in the ferromagnetic XXZ chain, and, in-between, at all temperatures in the XY chain. We find that the converse effect also occurs in the Antiferromagnetic XXZ chain: an Antiferromagnetic s_i^z s_j^z interaction induces a correlation in the s_i^xy component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or XY) anisotropy; (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
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excitation spectrum gap and spin wave velocity of x x z heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic $XXZ$ spin-$\frac{1}{2}$ Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated throughout the entire temperature and anisotropy ranges in both ferromagnetic and Antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the Antiferromagnetic spin-liquid spin-wave velocity and the Ising-like ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction ${s}_{i}^{x}{s}_{j}^{x}+{s}_{i}^{y}{s}_{j}^{y}$ induces an Antiferromagnetic correlation in the out-of-plane ${s}_{i}^{z}$ component, at higher temperatures in the Antiferromagnetic $XXZ$ chain, dominantly at low temperatures in the ferromagnetic $XXZ$ chain, and, in-between, at all temperatures in the $XY$ chain. We find that the converse effect also occurs in the Antiferromagnetic $XXZ$ chain: an Antiferromagnetic ${s}_{i}^{z}{s}_{j}^{z}$ interaction induces a correlation in the ${s}_{i}^{xy}$ component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or $XY$) of anisotropy; and (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
Nihat A Berker - One of the best experts on this subject based on the ideXlab platform.
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excitation spectrum gap and spin wave velocity of xxz heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic XXZ spin-1/2 Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated thoughout the entire temperature and anisotropy ranges in both ferromagnetic and Antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the Antiferromagnetic spin-liquid spin-wave velocity and the Isinglike ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction s_i^x s_j^x + s_i^y s_j^y induces an Antiferromagnetic correlation in the out-of-plane s_i^z component, at higher temperatures in the Antiferromagnetic XXZ chain, dominantly at low temperatures in the ferromagnetic XXZ chain, and, in-between, at all temperatures in the XY chain. We find that the converse effect also occurs in the Antiferromagnetic XXZ chain: an Antiferromagnetic s_i^z s_j^z interaction induces a correlation in the s_i^xy component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or XY) anisotropy; (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
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excitation spectrum gap and spin wave velocity of x x z heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic $XXZ$ spin-$\frac{1}{2}$ Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated throughout the entire temperature and anisotropy ranges in both ferromagnetic and Antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the Antiferromagnetic spin-liquid spin-wave velocity and the Ising-like ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction ${s}_{i}^{x}{s}_{j}^{x}+{s}_{i}^{y}{s}_{j}^{y}$ induces an Antiferromagnetic correlation in the out-of-plane ${s}_{i}^{z}$ component, at higher temperatures in the Antiferromagnetic $XXZ$ chain, dominantly at low temperatures in the ferromagnetic $XXZ$ chain, and, in-between, at all temperatures in the $XY$ chain. We find that the converse effect also occurs in the Antiferromagnetic $XXZ$ chain: an Antiferromagnetic ${s}_{i}^{z}{s}_{j}^{z}$ interaction induces a correlation in the ${s}_{i}^{xy}$ component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or $XY$) of anisotropy; and (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
Rembert A. Duine - One of the best experts on this subject based on the ideXlab platform.
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Antiferromagnetic magnons as highly squeezed fock states underlying quantum correlations
Physical Review B, 2019Co-Authors: Akashdeep Kamra, Even Thingstad, Gianluca Rastelli, Arne Brataas, Wolfgang Belzig, Rembert A. Duine, Asle SudbøAbstract:Employing the concept of two-mode squeezed states from quantum optics, we demonstrate a revealing physical picture for the Antiferromagnetic ground state and excitations. Superimposed on a Neel ordered configuration, a spin-flip restricted to one of the sublattices is called a sublattice magnon. We show that an Antiferromagnetic spin-up magnon is composed of a quantum superposition of states with n+1 spin-up and n spin-down sublattice magnons and is thus an enormous excitation despite its unit net spin. Consequently, its large sublattice spin can amplify its coupling to other excitations. Employing von Neumann entropy as a measure, we show that the Antiferromagnetic eigenmodes manifest a high degree of entanglement between the two sublattices, thereby establishing antiferromagnets as reservoirs for strong quantum correlations. Based on these insights, we outline strategies for exploiting the strong quantum character of Antiferromagnetic (squeezed) magnons and give an intuitive explanation for recent experimental and theoretical findings in Antiferromagnetic magnon spintronics.
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tunable long distance spin transport in a crystalline Antiferromagnetic iron oxide
Nature, 2018Co-Authors: Romain Lebrun, Arne Brataas, Rembert A. Duine, Andrew Ross, Scott A Bender, Alireza Qaiumzadeh, Lorenzo Baldrati, Joel CramerAbstract:Spintronics relies on the transport of spins, the intrinsic angular momentum of electrons, as an alternative to the transport of electron charge as in conventional electronics. The long-term goal of spintronics research is to develop spin-based, low-dissipation computing-technology devices. Recently, long-distance transport of a spin current was demonstrated across ferromagnetic insulators1. However, Antiferromagnetically ordered materials, the most common class of magnetic materials, have several crucial advantages over ferromagnetic systems for spintronics applications2: antiferromagnets have no net magnetic moment, making them stable and impervious to external fields, and can be operated at terahertz-scale frequencies3. Although the properties of antiferromagnets are desirable for spin transport4–7, indirect observations of such transport indicate that spin transmission through antiferromagnets is limited to only a few nanometres8–10. Here we demonstrate long-distance propagation of spin currents through a single crystal of the Antiferromagnetic insulator haematite (α-Fe2O3)11, the most common Antiferromagnetic iron oxide, by exploiting the spin Hall effect for spin injection. We control the flow of spin current across a haematite–platinum interface—at which spins accumulate, generating the spin current—by tuning the Antiferromagnetic resonance frequency using an external magnetic field12. We find that this simple Antiferromagnetic insulator conveys spin information parallel to the Antiferromagnetic Neel order over distances of more than tens of micrometres. This mechanism transports spins as efficiently as the most promising complex ferromagnets1. Our results pave the way to electrically tunable, ultrafast, low-power, Antiferromagnetic-insulator-based spin-logic devices6,13 that operate without magnetic fields at room temperature.
Ozan S Sariyer - One of the best experts on this subject based on the ideXlab platform.
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excitation spectrum gap and spin wave velocity of xxz heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic XXZ spin-1/2 Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated thoughout the entire temperature and anisotropy ranges in both ferromagnetic and Antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the Antiferromagnetic spin-liquid spin-wave velocity and the Isinglike ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction s_i^x s_j^x + s_i^y s_j^y induces an Antiferromagnetic correlation in the out-of-plane s_i^z component, at higher temperatures in the Antiferromagnetic XXZ chain, dominantly at low temperatures in the ferromagnetic XXZ chain, and, in-between, at all temperatures in the XY chain. We find that the converse effect also occurs in the Antiferromagnetic XXZ chain: an Antiferromagnetic s_i^z s_j^z interaction induces a correlation in the s_i^xy component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or XY) anisotropy; (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
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excitation spectrum gap and spin wave velocity of x x z heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic $XXZ$ spin-$\frac{1}{2}$ Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated throughout the entire temperature and anisotropy ranges in both ferromagnetic and Antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the Antiferromagnetic spin-liquid spin-wave velocity and the Ising-like ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction ${s}_{i}^{x}{s}_{j}^{x}+{s}_{i}^{y}{s}_{j}^{y}$ induces an Antiferromagnetic correlation in the out-of-plane ${s}_{i}^{z}$ component, at higher temperatures in the Antiferromagnetic $XXZ$ chain, dominantly at low temperatures in the ferromagnetic $XXZ$ chain, and, in-between, at all temperatures in the $XY$ chain. We find that the converse effect also occurs in the Antiferromagnetic $XXZ$ chain: an Antiferromagnetic ${s}_{i}^{z}{s}_{j}^{z}$ interaction induces a correlation in the ${s}_{i}^{xy}$ component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or $XY$) of anisotropy; and (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
Allan H. Macdonald - One of the best experts on this subject based on the ideXlab platform.
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Topological Antiferromagnetic spintronics
Nature Physics, 2018Co-Authors: Libor Šmejkal, Binghai Yan, Yuriy Mokrousov, Allan H. MacdonaldAbstract:The recent demonstrations of electrical manipulation and detection of Antiferromagnetic spins have opened up a new chapter in the story of spintronics. Here, we review the emerging research field that is exploring the links between Antiferromagnetic spintronics and topological structures in real and momentum space. Active topics include proposals to realize Majorana fermions in Antiferromagnetic topological superconductors, to control topological protection and Dirac points by manipulating Antiferromagnetic order parameters, and to exploit the anomalous and topological Hall effects of zero-net-moment antiferromagnets. We explain the basic concepts behind these proposals, and discuss potential applications of topological Antiferromagnetic spintronics.
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Antiferromagnetic metal spintronics
Philosophical Transactions of the Royal Society A, 2011Co-Authors: Allan H. Macdonald, Maxim TsoiAbstract:In this brief review, we explain the theoretical basis for the notion that spin-transfer torques (STTs) and giant-magnetoresistance effects can, in principle, occur in circuits containing only normal and Antiferromagnetic (AFM) materials, and for the notion that antiferromagnets can play a role in STT phenomena in circuits containing both ferromagnetic and AFM elements. We review the experimental literature that provides partial evidence for these AFM spintronic effects but demonstrates that, like exchange-bias effects, they are sensitive to details of interface structure that are not always under experimental control. Finally, we speculate briefly on some strategies that might advance progress.
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theory of spin torques and giant magnetoresistance in Antiferromagnetic metals
Physical Review B, 2006Co-Authors: Alvaro S Nunez, Paul M. Haney, R A Duine, Allan H. MacdonaldAbstract:Spintronics in ferromagnetic metals is built on a complementary set of phenomena in which magnetic configurations influence transport coefficients and transport currents alter magnetic configurations. Here, we propose that corresponding effects occur in circuits containing Antiferromagnetic metals. The critical current for order parameter orientation switching can be smaller in the Antiferromagnetic case because of the absence of shape anisotropy and because spin torques can act through the entire volume of an antiferromagnet. We discuss possible applications of Antiferromagnetic metal spintronics.
