Thermodynamics of itinerant metamagnetic transitions

TL;DR

This paper explores how van Hove singularities influence the thermodynamics and magnetic transitions in 2D systems, revealing phenomena like shifted critical fields and double-peak specific heat structures, which mimic non-Fermi liquid behavior.

Contribution

It demonstrates that a van Hove singularity can cause complex thermodynamic phenomena and apparent non-Fermi liquid behavior at mean-field level, advancing understanding of metamagnetic transitions.

Findings

Peak in density of states raises critical field.

Creates double-peak structure in specific heat.

Can cause non-Fermi liquid-like behavior.

Abstract

Theoretical studies of the metamagnetism and anomalous phase of Sr3Ru2O7 have focused on the role of van Hove singularities, although much experimental evidence points towards quantum criticality having a large effect. We investigate the magnetic and thermodynamic properties of systems where magnetic field tunes through such a peak in the electronic density of states. We study the generic case of a van Hove singularity in 2D. We see that in combination with the requirement of number conservation and interaction effects the peak in the density of states produces several interesting phenomena including raising the critical field of the transition above naive estimates, altering the relationship between temperature and field scales and creating a distinctive double-peak structure in the electronic specific heat. We show that this apparent non-Fermi liquid behaviour can be caused at mean-field level by a peak in the density of states.