The Experts below are selected from a list of 88353 Experts worldwide ranked by ideXlab platform
Shou-cheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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the quantum anomalous Hall Effect theory and experiment
Annual Review of Condensed Matter Physics, 2016Co-Authors: Chao-xing Liu, Shou-cheng ZhangAbstract:The quantum anomalous Hall Effect is defined as a quantized Hall Effect realized in a system without an external magnetic field. The quantum anomalous Hall Effect is a novel manifestation of topological structure in many-electron systems and may have potential applications in future electronic devices. In recent years, the quantum anomalous Hall Effect was proposed theoretically and realized experimentally. In this review article, we provide a systematic overview of the theoretical and experimental developments in this field.
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the quantum spin Hall Effect
Annual Review of Condensed Matter Physics, 2011Co-Authors: Joseph Maciejko, Taylor L Hughes, Shou-cheng ZhangAbstract:Most quantum states of condensed matter are classified by the symmetries they break. For example, crystalline solids break translational symmetry, and ferromagnets break rotational symmetry. By contrast, topological states of matter evade traditional symmetry-breaking classification schemes, and they signal the existence of a fundamentally different organizational principle of quantum matter. The integer and fractional quantum Hall Effects were the first topological states to be discovered in the 1980s, but they exist only in the presence of large magnetic fields. The search for topological states of matter that do not require magnetic fields for their observation led to the theoretical prediction in 2006 and experimental observation in 2007 of the so-called quantum spin Hall Effect in HgTe quantum wells, a new topological state of quantum matter. In this article, we review the theoretical foundations and experimental discovery of the quantum spin Hall Effect.
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quantum anomalous Hall Effect inhg1 ymnytequantum wells
Physical Review Letters, 2008Co-Authors: Chao-xing Liu, Xi Dai, Zhong Fang, Shou-cheng ZhangAbstract:The quantum Hall Effect is usually observed when a two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall Effect, can be realized in Hg1 yMnyTe quantum wells, without an external magnetic field and the associated Landau levels. This Effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This Effect enables dissipationless charge current in spintronics devices.
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quantum anomalous Hall Effect in hg1 ymnyte quantum wells
Physical Review Letters, 2008Co-Authors: Xi Dai, Chao-xing Liu, Zhong Fang, Shou-cheng ZhangAbstract:The quantum Hall Effect is usually observed when a two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall Effect, can be realized in ${\mathrm{Hg}}_{1\ensuremath{-}y}{\mathrm{Mn}}_{y}\mathrm{Te}$ quantum wells, without an external magnetic field and the associated Landau levels. This Effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This Effect enables dissipationless charge current in spintronics devices.
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Quantum spin Hall Effect
Physical Review Letters, 2006Co-Authors: B. Andrei Bernevig, Shou-cheng ZhangAbstract:The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall Effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall Effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of $2 \frac{e}{4\pi}$. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.
Eiji Saitoh - One of the best experts on this subject based on the ideXlab platform.
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inverse spin Hall Effect in palladium at room temperature
Journal of Applied Physics, 2010Co-Authors: Kazuya Ando, Eiji SaitohAbstract:The inverse spin-Hall Effect, conversion of a spin current into electromotive force, has been investigated in a simple Ni81Fe19/Pd film using the spin pumping. In the Ni81Fe19/Pd film, a spin current generated by the spin pumping is converted into an electromotive force using the inverse spin-Hall Effect in the Pd layer. From the magnitude of the electromotive force, we estimated the spin-Hall angle for Pd as 0.01. This large spin-Hall angle for Pd is consistent with the prediction from the Gilbert damping enhancement due to the spin pumping. This value will be a crucial piece of information for spintronics device engineering.
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inverse spin Hall Effect induced by spin pumping in different thickness pt films
IEEE Transactions on Magnetics, 2010Co-Authors: Hiroyasu Nakayama, Kazuya Ando, K. Harii, Y Kajiwara, T Yoshino, K Uchida, Eiji SaitohAbstract:The inverse spin-Hall Effect, conversion of spin currents into electromotive force, has been investigated in Pt thin films with changing the thickness of the Pt films. We measured the electric voltage due to the inverse spin-Hall Effect induced by the spin pumping in Ni81Fe19/Pt bilayer systems with different Pt thickness films (d N=10, 30, 50, and 75 nm) at room temperature. The experimental results show that the signal induced by the inverse spin-Hall Effect V ISHE is inversely proportional to the Pt thickness d N, which is well reproduced by a simple equivalent circuit model.
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Electric manipulation of spin relaxation using the spin Hall Effect.
Physical review letters, 2008Co-Authors: Kazuya Ando, Saburo Takahashi, K. Harii, K. Sasage, Jun'ichi Ieda, Sadamichi Maekawa, Eiji SaitohAbstract:Using the spin Hall Effect, magnetization relaxation in a Ni_{81}Fe_{19}/Pt film is manipulated electrically. An electric current applied to the Pt layer exerts spin torque on the entire magnetization of the Ni81Fe19 layer via the macroscopic spin transfer induced by the spin Hall Effect and modulates the magnetization relaxation in the Ni81Fe19 layer. This method allows us to tune the magnetization dynamics regardless of the film size without applying electric currents directly to the magnetic layer.
Chao-xing Liu - One of the best experts on this subject based on the ideXlab platform.
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the quantum anomalous Hall Effect theory and experiment
Annual Review of Condensed Matter Physics, 2016Co-Authors: Chao-xing Liu, Shou-cheng ZhangAbstract:The quantum anomalous Hall Effect is defined as a quantized Hall Effect realized in a system without an external magnetic field. The quantum anomalous Hall Effect is a novel manifestation of topological structure in many-electron systems and may have potential applications in future electronic devices. In recent years, the quantum anomalous Hall Effect was proposed theoretically and realized experimentally. In this review article, we provide a systematic overview of the theoretical and experimental developments in this field.
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quantum anomalous Hall Effect inhg1 ymnytequantum wells
Physical Review Letters, 2008Co-Authors: Chao-xing Liu, Xi Dai, Zhong Fang, Shou-cheng ZhangAbstract:The quantum Hall Effect is usually observed when a two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall Effect, can be realized in Hg1 yMnyTe quantum wells, without an external magnetic field and the associated Landau levels. This Effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This Effect enables dissipationless charge current in spintronics devices.
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quantum anomalous Hall Effect in hg1 ymnyte quantum wells
Physical Review Letters, 2008Co-Authors: Xi Dai, Chao-xing Liu, Zhong Fang, Shou-cheng ZhangAbstract:The quantum Hall Effect is usually observed when a two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall Effect, can be realized in ${\mathrm{Hg}}_{1\ensuremath{-}y}{\mathrm{Mn}}_{y}\mathrm{Te}$ quantum wells, without an external magnetic field and the associated Landau levels. This Effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This Effect enables dissipationless charge current in spintronics devices.
Jainendra K. Jain - One of the best experts on this subject based on the ideXlab platform.
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phase diagram of the two component fractional quantum Hall Effect
Physical Review Letters, 2013Co-Authors: Alexander C Archer, Jainendra K. JainAbstract:We calculate the phase diagram of the two component fractional quantum Hall Effect as a function of the spin or valley Zeeman energy and the filling factor, which reveals new phase transitions and phase boundaries spanning many fractional plateaus. This phase diagram is relevant to the fractional quantum Hall Effect in graphene and in GaAs and AlAs quantum wells, when either the spin or valley degree of freedom is active.
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fractional quantum Hall Effect in graphene
Physical Review B, 2006Co-Authors: Csaba Tőke, Paul E Lammert, Vincent H Crespi, Jainendra K. JainAbstract:Unlike regular electron spin, the pseudospin degeneracy of Fermi points in graphene does not couple directly to magnetic field. Therefore graphene provides a natural vehicle to observe the integral and fractional quantum Hall physics in an elusive limit analogous to zero Zeeman splitting in GaAs systems. This limit can exhibit new integral plateaus arising from interactions, large pseudoskyrmions, fractional sequences, even/odd numerator Effects, composite-fermion pseudoskyrmions, and a pseudospin-singlet composite-fermion Fermi sea. It is stressed that the Dirac nature of the $B=0$ spectrum, which induces qualitative changes in the overall spectrum, has no bearing on the fractional quantum Hall Effect in the $n=0$ Landau level of graphene. The second Landau level of graphene is predicted to show more robust fractional quantum Hall Effect than the second Landau level of GaAs.
Shufeng Zhang - One of the best experts on this subject based on the ideXlab platform.
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intrinsic spin and orbital angular momentum Hall Effect
Physical Review Letters, 2005Co-Authors: Shufeng Zhang, Zenghui YangAbstract:A generalized definition of intrinsic and extrinsic transport coefficients is introduced. We show that transport coefficients from the intrinsic origin are solely determined by local electronic structure, and thus the intrinsic spin Hall Effect is not a transport phenomenon. The intrinsic spin Hall current is always accompanied by an equal but opposite intrinsic orbital angular momentum Hall current. We prove that the intrinsic spin Hall Effect does not induce a spin accumulation at the edge of the sample or near the interface.
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Spin Hall Effect in the Presence of Spin Diffusion
Physical review letters, 2000Co-Authors: Shufeng ZhangAbstract:Hirsch [Phys. Rev. Lett. 83, 1834 (1999)] recently proposed a spin Hall Effect based on the anomalous scattering mechanism in the absence of spin-flip scattering. Since the anomalous scattering causes both anomalous currents and a finite spin-diffusion length, we derive the spin Hall Effect in the presence of spin diffusion from a semiclassical Boltzmann equation. When the formulation is applied to certain metals and semiconductors, the magnitude of the spin Hall voltage due to the spin accumulation is found to be much larger than that of magnetic multilayers. An experiment is proposed to measure this spin Hall Effect.
