The high-field Fermi surface of YbRh2Si2

TL;DR

This study investigates the Fermi surface of YbRh2Si2 at high magnetic fields using quantum oscillation measurements, revealing complexities in distinguishing between small and large Fermi surface configurations due to spin-splitting effects.

Contribution

It provides detailed quantum oscillation data at high fields and discusses the challenges in interpreting Fermi surface topology in correlated electron systems.

Findings

High-field measurements above 10 T show complex Fermi surface behavior.

Spin-split branches can mimic different Fermi surface configurations.

Comparison with calculations highlights the difficulty in Fermi surface identification.

Abstract

We present quantum oscillation measurements of YbRh2Si2 at magnetic fields above the Kondo-suppression scale H0 ~ 10 T. Comparison with electronic structure calculations is complicated because the "small" Fermi surface, where the Yb 4f-quasi-hole is not contributing to the Fermi volume, and "large" Fermi surface, where the Yb 4f-quasi-hole is contributing to the Fermi volume, are related by a rigid Fermi energy shift. This means that spin-split branches of the large Fermi surface can look like unsplit branches of the small surface, and vice-versa. Thus, although the high-field angle dependence of the experimentally-measured oscillation frequencies most resembles the electronic structure prediction for the small Fermi surface, this may instead be a branch of the spin-split large Fermi surface.