Inhomogeneity identification by measuring magnetic quantum oscillations

TL;DR

This paper presents a method to identify sample inhomogeneity by analyzing magnetic quantum oscillations, revealing differences in Fermi energy distribution and phase behavior between homogeneous and inhomogeneous samples of NbSb$_2$.

Contribution

It introduces a novel approach to detect material inhomogeneity through magnetic quantum oscillation analysis, highlighting the impact of Fermi energy distribution asymmetry.

Findings

Inhomogeneous samples show phase shifts and amplitude anomalies in quantum oscillations.

Homogeneous samples fit symmetric Fermi energy models, while inhomogeneous ones require asymmetric models.

The method helps avoid misinterpretation of quantum oscillation data in topological materials.

Abstract

This study explores the identification of sample inhomogeneity via magnetic quantum oscillations analysis in semimetal NbSb$_2$. By doping Bi and Cr, we obtained a homogeneous Bi-doped sample and an inhomogeneous Cr-doped sample, whose homogeneity was confirmed by comparing the magnetic quantum oscillation before and after grinding the samples. The magnetic quantum oscillations in the inhomogeneous sample exhibited a distinct phase shift and unusual field-dependent amplitude, believed to result from a non-uniform Fermi energy. The analysis of the magnetic quantum oscillations demonstrated that the homogeneous Bi-doped sample can be interpreted by the symmetric and Lorentzian effective Fermi energy distribution, while the inhomogeneous Cr-doped sample exhibited an asymmetric distribution, illustrating an unconventional violation of the Lifshitz-Kosevich formula. This research provides a novel method for identifying material inhomogeneity and mitigating potential misinterpretations of magnetic quantum oscillations' unusual phase, commonly seen as a nontrivial Berry phase indicator in topological materials studies.