Magnetic Oscillations Induced by Phonons in Non-Magnetic Materials

Abstract

The authors show that, similarly to electrons, in the presence of spin-orbit coupling, phonons can induce an effective magnetic oscillation even in non-magnetic materials, and therefore can act as an additional spin-flipping mechanism in electron-phonon physics.

An unexpected finding two decades ago demonstrated that Shockley electron states in noble metal surfaces are spin-polarized, forming a circulating spin texture in reciprocal space. The fundamental role played by the spin degree of freedom was then revealed, even for a non-magnetic system, whenever the spin-orbit coupling was present with some strength. Here, we demonstrate that, similarly to electrons in the presence of spin-orbit coupling, the propagating vibrational modes are also accompanied by a well-defined magnetic oscillation even in non-magnetic materials. Although this effect is illustrated by considering a single layer of the WSe2 dichalogenide, the phenomenon is completely general and valid for any non-magnetic material with spin-orbit coupling. The emerging phonon-induced magnetic oscillation acts as an additional effective flipping mechanism for the electron spin and its implications in the transport and scattering properties of the material are evident and profound.