Magnetism Induced by Periodically Driven Nonmagnetic Impurities on Surfaces with Spin-Orbit Coupling.

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's function method within the Keldysh formalism, computing the nonequilibrium 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 nonlocal momentum space, which helps uncover the physical origin of the induced magnetic field in terms of Fermi surface spin polarization and the system's dynamical character.