Simple mechanisms that impede the Berry phase identification from magneto-oscillations

TL;DR

This paper discusses how simple factors like chemical potential shifts and system nonuniformity can significantly distort the observed Berry phase in magneto-oscillation experiments, complicating topological system identification.

Contribution

It identifies two mechanisms that can impede accurate Berry phase detection in magneto-oscillations, emphasizing the need for careful analysis in topological insulator studies.

Findings

Magnetic field dependence of chemical potential affects phase measurements.

System nonuniformity can alter the observed magneto-oscillation phase.

These mechanisms are relevant to both trivial and non-trivial topological systems.

Abstract

The phase of quantum magneto-oscillations is often associated with the Berry phase and is widely used to argue in favor of topological nontriviality of the system (Berry phase $2\pi n+\pi$). Nevertheless, the experimentally determined value may deviate from $2\pi n+\pi$ arbitrarily, therefore more care should be made analyzing the phase of magneto-oscillations to distinguish trivial systems from nontrivial. In this paper we suggest two simple mechanisms dramatically affecting the experimentally observed value of the phase in three-dimensional topological insulators: (i) magnetic field dependence of the chemical potential, and (ii) possible nonuniformity of the system. These mechanisms are not limited to topological insulators and can be extended to other topologically trivial and non-trivial systems.