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Anisotropic conductivity of disordered 2DEGs due to spin-orbit interactions  [PDF]
Oleg Chalaev,Daniel Loss
Physics , 2007, DOI: 10.1103/PhysRevB.77.115352
Abstract: We show that the conductivity tensor of a disordered two-dimensional electron gas becomes anisotropic in the presence of both Rashba and Dresselhaus spin-orbit interactions (SOI). This anisotropy is a mesoscopic effect and vanishes with vanishing charge dephasing time. Using a diagrammatic approach including zero, one, and two-loop diagrams, we show that a consistent calculation needs to go beyond a Boltzmann equation approach. In the absence of charge dephasing and for zero frequency, a finite anisotropy \sigma_{xy} e^2/lhpf arises even for infinitesimal SOI.
Spin-Hall conductivity of a disordered 2D electron gas with Dresselhaus spin-orbit interaction  [PDF]
A. G. Mal'shukov,K. A. Chao
Physics , 2004, DOI: 10.1103/PhysRevB.71.121308
Abstract: The spin-Hall conductivity of a disordered 2D electron gas has been calculated for an arbitrary spin-orbit interaction. We have found that in the diffusive regime of electron transport, in accordance with previous calculations, the dc spin-Hall conductivity of a homogeneous system turns to zero due to impurity scattering when the spin-orbit coupling is represented only by the Rashba interaction. However, when the Dresselhaus interaction is taken into account, the spin-Hall current is not zero. We also considered the spin-Hall currents induced by an inhomogeneous electric field. It is shown that a time dependent electric charge induces a vortex of spin-Hall currents.
Spin-Hall conductivity due to Rashba spin-orbit interaction in disordered systems  [PDF]
Oleg Chalaev,Daniel Loss
Physics , 2004, DOI: 10.1103/PhysRevB.71.245318
Abstract: We consider the spin-Hall current in a disordered two-dimensional electron gas in the presence of Rashba spin-orbit interaction. We derive a generalized Kubo-Greenwood formula for the spin-Hall conductivity $\sigma$ and evaluate it in an systematic way using standard diagrammatic techniques for disordered systems. We find that in the diffusive regime both Boltzmann and the weak localization contributions to $\sigma$ are of the same order and vanish in the zero frequency limit. We show that the uniform spin current is given by the total time derivative of the magnetization from which we can conclude that the spin current vanishes exactly in the stationary limit. This conclusion is valid for arbitrary spin-independent disorder, external electric field strength, and also for interacting electrons.
Conductivity in Two-Dimensional Disordered Model with Anisotropic Long-Range Hopping  [PDF]
E. A. Dorofeev,S. I. Matveenko
Physics , 1998, DOI: 10.1134/1.558835
Abstract: We consider two-dimensional system of particles localized on randomly distributed sites of squared lattice with anisotropic transfer matrix elements between localized sites. By summing of "diffusion ladder" and "cooperon ladder" type vertices we calculated the conductivity for various sites and particles densities.
Quantum conductivity corrections in two dimensional long-range disordered systems with strong spin-orbit splitting of electron spectrum  [PDF]
Alexander P. Dmitriev,Igor V. Gornyi,Valentin Yu. Kachorovskii
Physics , 1998, DOI: 10.1134/1.567870
Abstract: We study quantum corrections to conductivity in a 2D system with a smooth random potential and strong spin-orbit splitting of the spectrum. We show that the interference correction is positive and down to the very low temperature can exceed the negative correction related to electron-electron interactions. We discuss this result in the context of the problem of the metal-insulator transition in Si-MOSFET structures.
Anisotropic universal conductance fluctuations in disordered quantum wires with Rashba and Dresselhaus spin-orbit interaction and applied in-plane magnetic field  [PDF]
Matthias Scheid,Inanc Adagideli,Junsaku Nitta,Klaus Richter
Physics , 2009, DOI: 10.1088/0268-1242/24/6/064005
Abstract: We investigate the transport properties of narrow quantum wires realized in disordered two-dimensional electron gases in the presence of k-linear Rashba and Dresselhaus spin-orbit interaction (SOI), and an applied in-plane magnetic field. Building on previous work [Scheid, et al., PRL 101, 266401 (2008)], we find that in addition to the conductance, the universal conductance fluctuations also feature anisotropy with respect to the magnetic field direction. This anisotropy can be explained solely from the symmetries exhibited by the Hamiltonian as well as the relative strengths of the Rashba and Dresselhaus spin orbit interaction and thus can be utilized to detect this ratio from purely electrical measurements.
Holographic Conductivity in Disordered Systems  [PDF]
Shinsei Ryu,Tadashi Takayanagi,Tomonori Ugajin
Physics , 2011, DOI: 10.1007/JHEP04(2011)115
Abstract: The main purpose of this paper is to holographically study the behavior of conductivity in 2+1 dimensional disordered systems. We analyze probe D-brane systems in AdS/CFT with random closed string and open string background fields. We give a prescription of calculating the DC conductivity holographically in disordered systems. In particular, we find an analytical formula of the conductivity in the presence of codimension one randomness. We also systematically study the AC conductivity in various probe brane setups without disorder and find analogues of Mott insulators.
Anisotropic conductivity in superconducting NCCO  [PDF]
U. Michelucci,A. P. Kampf,A. Pimenov
Physics , 2000,
Abstract: The low temperature behaviour of the in-plane and c-axis conductivity of electron-doped cuprates like NCCO is examined; it is shown to be consistent with an isotropic quasiparticle scattering rate and an anisotropic interlayer hopping parameter which is non-zero for planar momenta along the direction of the d$_{x^2-y^2}$ order parameter nodes. Based on these hypotheses we find that both, the in-plane and the c-axis conductivity, vary linearly with temperature, in agreement with experimental data at millimiter-wave frequencies.
Anisotropic optical conductivity and electron-hole asymmetry in doped monolayer graphene in the presence of the Rashba coupling  [PDF]
S. S. Sadeghi,A. Phirouznia,V. Fallahi
Physics , 2013, DOI: 10.1016/j.physe.2015.01.032
Abstract: In this study, the Optical conductivity of substitutionary doped graphene is investigated in presence of the Rashba spin orbit coupling (RSOC). Calculations have been performed within the coherent potential approximation (CPA) beyond the Dirac cone approximation. Results of the current study demonstrate that the optical conductivity is increased by increasing the RSOC strength. Meanwhile it was observed that the anisotropy of the band energy results in a considerable anisotropic optical conductivity (AOC) in monolayer graphene. The sign and magnitude of this anisotropic conductivity was shown to be controlled by the external field frequency. It was also shown that the Rashba interaction results in electron-hole asymmetry in monolayer graphene.
The nonlinear effects in 2DEG conductivity investigation by an acoustic method  [PDF]
I. L. Drichko,A. M. Diakonov,V. D. Kagan,A. M. Kreshchuk,T. A. Polyanskaya,I. G. Savel'ev,I. Yu. Smirnov,A. V. Suslov
Physics , 1997, DOI: 10.1002/(SICI)1521-3951(199801)205:1<357::AID-PSSB357>3.3.CO;2-B
Abstract: The parameters of two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure were determined by an acoustical (contactless) method in the delocalized electrons region ($B\le$2.5T). Nonlinear effects in Surface Acoustic Wave (SAW) absorption by 2DEG are determined by the electron heating in the electric field of SAW, which may be described in terms of electron temperature $T_e$. The energy relaxation time $\tau_{\epsilon}$ is determined by the scattering at piezoelectric potential of acoustic phonons with strong screening. At different SAW frequencies the heating depends on the relationship between $\omega\tau_{\epsilon}$ and 1 and is determined either by the instantaneously changing wave field ($\omega\tau_{\epsilon}$$<1$), or by the average wave power ($\omega\tau_{\epsilon}$$>1$).
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