Magnetism Induced by Periodically Driven Non-Magnetic Impurities on Surfaces with Spin-Orbit Coupling

TL;DR

This paper demonstrates that periodically driven non-magnetic impurities on surfaces with spin-orbit coupling can induce a complex, oscillating magnetization density, revealing new ways to control magnetic properties dynamically.

Contribution

It introduces a Floquet-Green function approach within the Keldysh formalism to analyze non-equilibrium magnetization in spin-orbit coupled systems under periodic driving.

Findings

Induced oscillating magnetization density without external magnetic field

Rich structure of magnetization dynamics revealed by Fourier analysis

Physical origin linked to Fermi surface spin polarization

Abstract

We investigate the response of the Rashba spin-orbit system to a time-periodic scalar potential, in order to determine whether an induced magnetization exists. We approach this by employing the Floquet-Green function method within the Keldysh formalism, computing the non-equilibrium steady state of the system. We find that, even in the absence of an external magnetic field, the system evolves into a state with an oscillating magnetization density that is remarkably rich in structure. We provide a detailed physical interpretation of the results by performing a Fourier decomposition in non-local momentum-space, which helps to uncover the physical origin of the induced magnetic field in terms of Fermi surface spin polarization and the system's dynamical character.