Collective modes in two- and three-dimensional electron systems with Rashba spin-orbit coupling

Abstract

In addition to charge plasmons, a 2D electron system with Rashba-type spin-orbit coupling (SOC) also supports three collective modes in the spin sector: the chiral-spin modes. We study the dispersions of the charge and spin modes and their coupling to each other within a generalized Random Phase Approximation for arbitrarily strong SOC, and both in 2D and 3D systems. In both 2D and 3D, we find that the charge plasmons are coupled to only one of the three chiral-spin modes. This coupling is shown to affect the dispersions of the modes at finite but not at zero wavenumbers. In 3D, the chiral-spin modes are strongly damped by particle-hole excitations and disappear for weak electron-electron interaction. Landau damping of the chiral-spin modes in 3D is directly related to the fact that, in contrast to 2D, there is no gap for particle-hole excitations between spin-split subbands. The gapless continuum is also responsible for Landau damping of the charge plasmon in 3D - a qualitatively new feature of the SOC system. We also discuss the optical conductivity of clean 2D and 3D systems and show that SOC introduces spectral weight at finite frequency in a such way that the sum rule is satisfied. The in-plane tranverse chiral-spin mode shows up as dispersing peak in the optical conductivity at finite number which can can be measured in the presence of diffraction grating. We also discuss possible experimental manifestations of chiral-spin modes in semiconductor quantum wells such InGaAs/AlGaAs and 3D giant Rashba materials of the BiTeI family.

31pp, 25 figs

References in corpus (13)

• Spin-Injection Spectroscopy of a Spin-Orbit Coupled Fermi Gas
• Strong spin-orbit splitting on Bi surfaces
• Measurement of Rashba and Dresselhaus spin-orbit magnetic fields
• Effect of electron-electron interactions on the conductivity of clean graphene
• Surface bound states and spin currents in non-centrosymmetric superconductors
• Transport equations for a two-dimensional electron gas with spin-orbit interaction
• Anisotropic current-induced spin accumulation in the two-dimensional electron gas with spin-orbit coupling
• Chiral spin resonance and spin-Hall conductivity in the presence of the electron-electron interactions
• Screening properties of the two-dimensional electron gas with spin-orbit coupling
• Plasmon mass and Drude weight in strongly spin-orbit-coupled 2D electron gases
• Spin-flip transitions induced by time-dependent electric fields in surfaces with strong spin-orbit interaction
• Optical Conductivity of a Two-Dimensional Electron Liquid with Spin-Orbit Interaction
• Tuning the Fermi level through the Dirac point of giant Rashba semiconductor BiTeI with pressure

Cited by in corpus (7)

• RKKY interaction in three-dimensional electron gases with linear spin-orbit coupling
• Chiral Spin Mode on the Surface of a Topological Insulator
• Optical spectral weight: comparison of weak and strong spin-orbit coupling
• Chiral Topological Excitons in a Chern Band Insulator
• Thermoelectric and optical probes for a Fermi surface topology change in noncentrosymmetric metals
• Coupled spin-charge dynamics in helical Fermi liquids beyond the random phase approximation
• Synergetic effect of spin-orbit coupling and Zeeman splitting on the optical conductivity in the one-dimensional Hubbard model