Phonon-assisted spin splitting in centrosymmetric crystals

TL;DR

This paper reveals that lattice vibrations combined with spin-orbit coupling can lift spin degeneracy in centrosymmetric crystals, demonstrated through first principles calculations on CsPbCl3, expanding possibilities for spintronic applications.

Contribution

It introduces a novel mechanism for spin splitting in symmetric crystals via phonon-assisted effects, supported by first principles calculations and experimental proposals.

Findings

Spin degeneracy can be lifted in centrosymmetric crystals with vibrations and spin-orbit coupling.

First principles calculations show spin splitting in CsPbCl3 at finite temperature.

Proposes optical and photoemission experiments to verify the effect.

Abstract

For static crystals it is well known that electronic states are doubly degenerate in their spin degree of freedom in the presence of time reversal and inversion symmetries. This degeneracy can only be lifted by either (i) breaking time reversal symmetry, for example in a ferromagnet, or (ii) breaking inversion symmetry and having spin orbit coupling, for example in the Rashba effect. We propose that spin degeneracy can be lifted in time reversal and inversion symmetric crystals with a combination of lattice vibrations and spin-orbit coupling. We demonstrate this effect in the cubic perovskite CsPbCl$_3$ by performing first principles calculations of the finite temperature band structure, which, in accordance with our prediction, undergoes spin splitting. We also suggest optical and photoemission experiments to examine our predictions. This new understanding dramatically expands the range of materials that can exhibit spin splitting, with potential applications in a variety of technologies such as spintronics and photovoltaics.