Universal Spin Dynamics in Quantum Wires

TL;DR

This paper explores the universal behavior of spin dynamics across various quasi-one-dimensional systems, revealing common underlying physics and observable effects like spin currents and polarization.

Contribution

It demonstrates that diverse systems such as narrow-gap semiconductors, graphene, and TMDCs share a unified Dirac-like Hamiltonian describing their spin phenomena.

Findings

Universal Dirac-like Hamiltonian for different systems

Equivalence of spin-dependent effects across systems

Clarification on spin-dependent position operator correction

Abstract

We discuss the universal spin dynamics in quasi one-dimensional systems including the real spin in narrow-gap semiconductors like InAs and InSb, the valley pseudospin in staggered single-layer graphene, and the combination of real spin and valley pseudospin characterizing single-layer transition metal dichalcogenides (TMDCs) such as MoS$_2$, WS$_2$, MoSe$_2$, and WSe$_2$. All these systems can be described by the same Dirac-like Hamiltonian. Spin-dependent observable effects in one of these systems thus have counterparts in each of the other systems. Effects discussed in more detail include equilibrium spin currents, current-induced spin polarization (Edelstein effect), and spin currents generated via adiabatic spin pumping. Our work also suggests that a long-debated spin-dependent correction to the position operator in single-band models should be absent.