Doping-induced band shifts and Lifshitz transitions in heavy-fermion metals

TL;DR

This paper investigates how carrier doping influences Lifshitz transitions in heavy-fermion metals, revealing complex band shift behaviors due to strong correlations and interplay between heavy and light bands, challenging naive estimates.

Contribution

It provides a microscopic analysis of doping effects on Fermi surface topology changes in heavy-fermion systems, emphasizing the role of band interplay and correlations.

Findings

Doped carriers populate heavy and light bands equally.

Heavy band shifts are non-rigid due to correlations.

Naive estimates based on specific heat are invalid.

Abstract

For some heavy-fermion compounds, it has been suggested that a Fermi-surface-changing Lifshitz transition, which can be driven, e.g., by varying an applied magnetic field, occurs inside the heavy- fermion regime. Here we discuss, based on microscopic calculations, how the location of such a transition can be influenced by carrier doping. Due to strong correlations, a heavy band does not shift rigidly with the chemical potential. Intriguingly, we find that the actual shift is determined by the interplay of heavy and additional light bands crossing the Fermi level: doped carriers tend to populate heavy and light bands equally, despite the fact that the latter contribute a small density of states of excitations only. This invalidates naive estimates of the transition shift based on the low-temperature specific heat of the heavy Fermi liquid. We discuss applications of our results.