Metamagnetism and Lifshitz Transitions in Models for Heavy Fermions

TL;DR

This paper studies metamagnetic transitions in heavy fermion models, showing that Lifshitz transitions, involving Fermi surface topology changes, are the primary mechanism over Kondo breakdown, using advanced computational methods.

Contribution

It demonstrates that Lifshitz transitions, rather than Kondo breakdown, drive metamagnetism in heavy fermion models through detailed dynamical mean field analysis.

Findings

Universal magnetization curves scale with lattice coherence temperature.

Lifshitz transitions cause Fermi surface topology changes.

Single-particle residue analysis favors Lifshitz transition scenario.

Abstract

We investigate metamagnetic transitions in models for heavy fermions by considering the doped Kondo lattice model in two dimensions. Results are obtained within the framework of dynamical mean field and dynamical cluster approximations. Universal magnetization curves for different temperatures and Kondo couplings develop upon scaling with the lattice coherence temperature. Furthermore, the coupling of the local moments to the magnetic field is varied to take into account the different Land\'e factors of localized and itinerant electrons. The competition between the lattice coherence scale and the Zeeman energy scale allows for two interpretations of the metamagnetism in heavy fermions: Kondo breakdown or Lifshitz transitions. By tracking the single-particle residue through the transition, we can uniquely conclude in favor of the Lifshitz transition scenario. In this scenario, a quasiparticle band drops below the Fermi energy which leads to a change in topology of the Fermi surface.