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Register a new userSpin Hall angle fluctuations in a disorder device
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Added by
Anderson Barbosa A. L. R. Barbosa
Publication date
2020
fields
Physics
and research's language is
English
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We investigate a disorderly mesoscopic device that supports spin-orbit interaction. The systemis connected to four semi-infinite leads embedded in the Landauer-Buttiker setup for quantumtransport and, according to our analysis, exhibits spin Hall angle fluctuations. We show analyticallyand numerically the fingerprint of the universal fluctuation of the polarization mediated by theconversion of charge current into spin current. Our investigation shows the complete compatibilityof our analytical and numerical results with the most recent experiments. Furthermore, we shownonzero and universal features of spin Hall effect in Rashba 2DEG with disorder. All the resultsshow the relevance of microscopic parameters for electronic transport with charge-spin conversionand, in many cases, inevitably lead to universal numbers.
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We discuss the transport properties of a quantum spin-Hall insulator with sizable Rashba spin-orbit coupling in a disk geometry. The presence of topologically protected helical edge states allows for the control and manipulation of spin polarized currents: when ferromagnetic leads are coupled to the quantum spin-Hall device, the ballistic conductance is modulated by the Rashba strength. Therefore, by tuning the Rashba interaction via an all-electric gating, it is possible to control the spin polarization of injected electrons.
Landauers principle states that erasure of each bit of information in a system requires at least a unit of energy $k_B T ln 2$ to be dissipated. In return, the blank bit may possibly be utilized to extract usable work of the amount $k_B T ln 2$, in keeping with the second law of thermodynamics. While in principle any collection of spins can be utilized as information storage, work extraction by utilizing this resource in principle requires specialized engines that are capable of using this resource. In this work, we focus on heat and charge transport in a quantum spin Hall device in the presence of a spin bath. We show how a properly initialized nuclear spin subsystem can be used as a memory resource for a Maxwells Demon to harvest available heat energy from the reservoirs to induce charge current that can power an external electrical load. We also show how to initialize the nuclear spin subsystem using applied bias currents which necessarily dissipate energy, hence demonstrating Landauers principle. This provides an alternative method of energy storage in an all-electrical device. We finally propose a realistic setup to experimentally observe a Landauer erasure/work extraction cycle.
We study the spin relaxation (SR) of a two-dimensional electron gas (2DEG) in the quantized Hall regime and discuss the role of spatial inhomogeneity effects on the relaxation. The results are obtained for small filling factors ($ ull 1$) or when the filling factor is close to an integer. In either case SR times are essentially determined by a smooth random potential. For small $ u$ we predict a magneto-confinement resonance manifested in the enhancement of the SR rate when the Zeeman energy is close to the spacing of confinement sublevels in the low-energy wing of the disorder-broadened Landau level. In the resonant region the $B$-dependence of the SR time has a peculiar non-monotonic shape. If $ usimeq 2n+1$, the SR is going non-exponentially. Under typical conditions the calculated SR times range from $10^{-8}$ to $10^{-6} $s.
We study the disorder effect of resonant spin Hall effect in a two-dimension electron system with Rashba coupling in the presence of a tilted magnetic field. The competition between the Rashba coupling and the Zeeman coupling leads to the energy crossing of the Landau levels, which gives rise to the resonant spin Hall effect. Utilizing the Stredas formula within the self-consistent Born approximation, we find that the impurity scattering broadens the energy levels, and the resonant spin Hall conductance exhibits a double peak around the resonant point, which is recovered in an applied titled magnetic field.
Using a two-dimensional square lattice Heisenberg model with a Rashba-type Dzyaloshinskii-Moriya interaction, we demonstrate that chiral spin fluctuations can give rise to a thermal Hall effect in the absence of any static spin texture or momentum space topology. It is shown by means of Monte Carlo and stochastic spin dynamics simulations that the thermal Hall response is finite at elevated temperature outside of the linear spin wave regime and consistent with the presence of thermal fluctuation-induced nontrivial topology. Our result suggests that the high-fluctuation phases outside of the conventional regime of magnonics may yet be a promising area of exploration for spin-based electronics.
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