Impact of spin-orbit coupling on the Holstein polaron

TL;DR

This paper investigates how spin-orbit coupling influences the properties of polarons, revealing that it can both increase and decrease the effective mass depending on the coupling strength, with implications for material behavior.

Contribution

It provides a comprehensive numerical analysis of the impact of spin-orbit coupling on polaron ground state properties, confirming results with analytical methods and previous approximations.

Findings

Spin-orbit coupling increases effective mass at weak coupling.

It decreases effective mass at intermediate and strong coupling.

Large spin-orbit coupling can significantly lower polaron effective mass.

Abstract

We utilize an exact variational numerical procedure to calculate the ground state properties of a polaron in the presence of a Rashba-like spin orbit interaction. Our results corroborate with previous work performed with the Momentum Average approximation and with weak coupling perturbation theory. We find that spin orbit coupling increases the effective mass in the regime with weak electron phonon coupling, and decreases the effective mass in the intermediate and strong electron phonon coupling regime. Analytical strong coupling perturbation theory results confirm our numerical results in the small polaron regime. A large amount of spin orbit coupling can lead to a significant lowering of the polaron effective mass.