Interband scattering- and nematicity-induced quantum oscillation frequency in FeSe

TL;DR

This paper proposes a new explanation for the disappearance of a quantum oscillation frequency in FeSe related to nematicity, emphasizing interband scattering effects rather than Fermi surface topology changes.

Contribution

It introduces a generic, alternative scenario where nematicity and interband scattering cause quantum oscillation frequency changes independent of Fermi surface modifications.

Findings

A nematicity-induced quantum oscillation frequency can vanish without a Lifshitz transition.

Interband scattering mechanisms can produce observable quantum oscillation frequencies beyond the Onsager relation.

Implications for interpreting quantum oscillations in correlated materials are discussed.

Abstract

Understanding the nematic phase observed in the iron-chalcogenide materials is crucial for describing their superconducting pairing. Experiments on FeSe$_{1-x}$S$_x$ showed that one of the slow Shubnikov--de Haas quantum oscillation frequencies disappears when tuning the material out of the nematic phase via chemical substitution or pressure, which has been interpreted as a Lifshitz transition [Coldea et al., npj Quant Mater 4, 2 (2019), Reiss et al., Nat. Phys. 16, 89-94 (2020)]. Here, we present a generic, alternative scenario for a nematicity-induced sharp quantum oscillation frequency which disappears in the tetragonal phase and is not connected to an underlying Fermi surface pocket. We show that different microscopic interband scattering mechanisms - for example, orbital-selective scattering - in conjunction with nematic order can give rise to this quantum oscillation frequency beyond the standard Onsager relation. We discuss implications for iron-chalcogenides and the interpretation of quantum oscillations in other correlated materials.