scholarly journals Edge spin accumulation: Spin Hall effect without bulk spin current

2010 ◽  
Vol 81 (11) ◽  
Author(s):  
E. B. Sonin
Keyword(s):  
Hall Effect ◽  
Spin Current ◽  
Spin Hall Effect ◽  
Spin Accumulation ◽  
Edge Spin

scholarly journals Anomalous spin Hall and inverse spin Hall effects in magnetic systems

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
X. R. Wang
Keyword(s):  
Hall Effect ◽  
Order Parameter ◽  
Spin Current ◽  
Spin Hall Effect ◽  
Magnetic Systems ◽  
Charge Current ◽  
Spin Currents ◽  
Tensor Quantity ◽  
Hall Effects ◽  
Spin Hall Effects

AbstractSpin current is a very important tensor quantity in spintronics. However, the well-known spin-Hall effect (SHE) can only generate a few of its components whose propagating and polarization directions are perpendicular with each other and to an applied charge current. It is highly desirable in applications to generate spin currents whose polarization can be in any possible direction. Here anomalous SHE and inverse spin-Hall effect (ISHE) in magnetic systems are predicted. Spin currents, whose polarisation and propagation are collinear or orthogonal with each other and along or perpendicular to the charge current, can be generated, depending on whether the applied charge current is along or perpendicular to the order parameter. In anomalous ISHEs, charge currents proportional to the order parameter can be along or perpendicular to the propagating or polarization directions of the spin current.

EDGE MAGNETISM AND QUANTUM SPIN HALL EFFECT IN ZIGZAG GRAPHENE NANORIBBON

2013 ◽  
Vol 27 (15) ◽  
pp. 1362011 ◽  
Author(s):  
JUN-WON RHIM ◽  
KYUNGSUN MOON
Keyword(s):  
Electric Field ◽  
Hall Effect ◽  
Graphene Nanoribbon ◽  
Quantum Spin ◽  
Spin Hall Effect ◽  
Nonmonotonic Dependence ◽  
Quantum Spin Hall Effect ◽  
Edge Spin ◽  
Edge Band ◽  
Quantum Spin Hall

We present here a brief review on the remarkable consequences of the flat bands formed at the edges of the Zigzag graphene nanoribbon (ZGNR). The inclusion of the on-site Coulomb interaction is shown to induce the edge spin ferromagnetism, whose spin stiffness demonstrates a nonmonotonic dependence on the lateral electric field. The critical electric field strength corresponds to that of the insulator to half-metal transition. The inclusion of the spin–orbit coupling (SOC) has been believed to generate the quantum spin Hall effect (QSHE) guiding into the interesting new field of topological insulator. By carefully investigating the SOC near the edge, we have shown that the additional σ-edge band gives a marginal perturbation and hence the existence of the QSHE depends on the coupling strength between the π-edge bands and the σ-edge band. We demonstrate that for the charge neutral ZGNR, the QSHE does not occur in the pristine ZGNR, while the hydrogen passivation along the edge may recover the expected feature of the QSHE.

scholarly journals Orbital torque in magnetic bilayers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dongjoon Lee ◽  
Dongwook Go ◽  
Hyeon-Jong Park ◽  
Wonmin Jeong ◽  
Hye-Won Ko ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Hall Effect ◽  
Spin Current ◽  
Spin Hall Effect ◽  
Spin Orbit ◽  
Magnetic Torque ◽  
Device Applications ◽  
Metal Bilayers ◽  
Experiment Analysis ◽  
Theory And Experiment

AbstractThe orbital Hall effect describes the generation of the orbital current flowing in a perpendicular direction to an external electric field, analogous to the spin Hall effect. As the orbital current carries the angular momentum as the spin current does, injection of the orbital current into a ferromagnet can result in torque on the magnetization, which provides a way to detect the orbital Hall effect. With this motivation, we examine the current-induced spin-orbit torques in various ferromagnet/heavy metal bilayers by theory and experiment. Analysis of the magnetic torque reveals the presence of the contribution from the orbital Hall effect in the heavy metal, which competes with the contribution from the spin Hall effect. In particular, we find that the net torque in Ni/Ta bilayers is opposite in sign to the spin Hall theory prediction but instead consistent with the orbital Hall theory, which unambiguously confirms the orbital torque generated by the orbital Hall effect. Our finding opens a possibility of utilizing the orbital current for spintronic device applications, and it will invigorate researches on spin-orbit-coupled phenomena based on orbital engineering.

scholarly journals A New Approach to Transport Coefficients in the Quantum Spin Hall Effect

2020 ◽  
Author(s):  
Giovanna Marcelli ◽  
Gianluca Panati ◽  
Stefan Teufel
Keyword(s):  
Hall Effect ◽  
Constant Electric Field ◽  
Transport Coefficients ◽  
Spin Current ◽  
Spin Operator ◽  
Quantum Spin ◽  
Spin Hall Effect ◽  
Current Operator ◽  
Quantum Spin Hall Effect ◽  
Quantum Spin Hall

AbstractWe investigate some foundational issues in the quantum theory of spin transport, in the general case when the unperturbed Hamiltonian operator $$H_0$$ H 0 does not commute with the spin operator in view of Rashba interactions, as in the typical models for the quantum spin Hall effect. A gapped periodic one-particle Hamiltonian $$H_0$$ H 0 is perturbed by adding a constant electric field of intensity $$\varepsilon \ll 1$$ ε ≪ 1 in the j-th direction, and the linear response in terms of a S-current in the i-th direction is computed, where S is a generalized spin operator. We derive a general formula for the spin conductivity that covers both the choice of the conventional and of the proper spin current operator. We investigate the independence of the spin conductivity from the choice of the fundamental cell (unit cell consistency), and we isolate a subclass of discrete periodic models where the conventional and the proper S-conductivity agree, thus showing that the controversy about the choice of the spin current operator is immaterial as far as models in this class are concerned. As a consequence of the general theory, we obtain that whenever the spin is (almost) conserved, the spin conductivity is (approximately) equal to the spin-Chern number. The method relies on the characterization of a non-equilibrium almost-stationary state (NEASS), which well approximates the physical state of the system (in the sense of space-adiabatic perturbation theory) and allows moreover to compute the response of the adiabatic S-current as the trace per unit volume of the S-current operator times the NEASS. This technique can be applied in a general framework, which includes both discrete and continuum models.

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