Holstein magneto-polarons: from Landau levels to Hofstadter butterflies

TL;DR

This paper investigates the behavior of Holstein polarons in magnetic fields, revealing a distorted Hofstadter spectrum at strong fields and novel non-perturbational Landau level behavior at weak fields.

Contribution

It introduces non-perturbational methods to analyze Holstein polarons in magnetic fields, uncovering new spectral features and behaviors.

Findings

Polaron exhibits a distorted Hofstadter spectrum at strong fields.

Identifies non-perturbational Landau level behavior at weak fields.

Spectrum is of lower symmetry than that of a bare particle.

Abstract

We study the Holstein polaron in transverse magnetic field using non-perturbational methods. At strong fields and large coupling, we show that the polaron has a Hofstadter spectrum, however very distorted and of lower symmetry than that of a (heavier) bare particle. For weak magnetic fields, we identify non-perturbational behaviour of the Landau levels not previously known.