Isotropic Spin-orbit Coupling Research Articles

Thermodynamic properties of noninteracting quantum gases with spin-orbit coupling

In this brief report we study thermodynamic properties of noninteracting quantum gases with isotropic spin-orbit coupling. At high temperature, coefficients of virial expansion depend on both temperature $T$ and spin-orbit coupling strength $\ensuremath{\kappa}$. For strong coupling, virial expansion is applicable to the temperature region below the conventional degenerate temperature ${T}_{\mathrm{F}}$. At low temperature, specific heat is proportional to $\sqrt{T}$ in Bose gases and $T$ in Fermi gases. Temperature dependence of the chemical potential of fermions shows a different behavior when the Fermi surface is above and below the Dirac point.

Paired superfluidity and fractionalized vortices in systems of spin-orbit coupled bosons

In this Rapid Communication we study finite-temperature properties of spin-$1/2$ interacting bosons with spin-orbit coupling in two dimensions. When the ground state has stripe order, we show that thermal fluctuations will first melt the stripe order and lead to a superfluid of boson pairs if the spin-orbit coupling is isotropic or nearly isotropic. Such a phase supports fractionalized quantum vortices. The Kosterlitz-Thouless transition from superfluid to normal state is driven by proliferation of half vortices. When the ground state is a plane-wave state, the transition to normal state is driven by conventional Kosterlitz-Thouless transition. However, the critical temperature will drop to zero for isotropic spin-orbit coupling.

Tunable crossovers for the quantum interference correction to conductance and shot-noise power in chaotic quantum dots with nonideal contacts

We study a large class of tunable crossovers between the three Dyson universality classes for electron transport through chaotic quantum dots with nonideal contacts. We present analytical expressions for the leading quantum interference corrections to both the conductance and the shot-noise power as a function of the transparencies of the contacts and some tunable crossover parameters, such as a perpendicular magnetic field and spin-orbit coupling strengths. Our results apply both to metallic grains with isotropic spin-orbit coupling and to GaAs heterostructures, in which spin-orbit coupling arises from both the asymmetry of the confining potential and crystal inversion asymmetry. We found that, for nonideal contacts and in the absence of spin-orbit coupling, a perpendicular magnetic field can induce a surprising change of sign in the leading quantum interference correction to the shot-noise power. The results for metallic grains are recovered by independent calculations using quantum circuit theory.

Anisotropic dynamical spin-density response in quantum wells with spin-orbit interaction

The electric field-induced spin polarization of a two-dimensional electron gas with spin-orbit interaction is investigated in the frequency domain. We calculate the spin-polarizability tensor using the linear-response theory, taking into account the presence of both Rashba and Dresselhaus spin-orbit couplings. We consider quantum wells grown in the main crystallographic directions and concentrate on the high-frequency response in the collisionless regime. For an anisotropic spin splitting, it is shown that the spin-density response becomes dependent on the direction of the applied electric field and presents characteristic spectral features, in notable contrast to the case of an isotropic spin-orbit coupling. Such behavior is explained in terms of the nonisotropic momentum space available for electric-dipole transitions and the presence of critical points. This anisotropic dynamic response suggests new possibilities of spin manipulation which could find spintronic applications.

Internal hindered rotations in polyatomic systems with the Jahn-Teller effect for a 2T⊗( ε + τ2) term in the limiting case of strong vibronic coupling

Point defects in crystals with cubic local symmetry in a Jahn-Teller electronic 2S+1T term with significant spin-orbit coupling are shown to have additional intrinsic spherical symmetry and additional integrals of motion if the conditions of the d-mode model (equal frequencies and equal vibronic coupling to E and T2 vibrations) are satisfied. As in the case without spin-orbit interaction considered by O'Brien for strong vibronic coupling, taking into consideration the isotropic spin-orbit coupling in the Jahn-Teller multimode 2S+1T(X)( epsilon + tau 2) problem, the lowest sheet of the adiabatic potential energy surface is shown to possess a two-dimensional trough. This determines the characteristic rotational energy spectrum of the system. If the conditions of the d-mode model are violated the trough becomes warped and rotations become hindered, and this is represented by appropriate changes in the rotational energy spectrum.