Universal signatures of the metamagnetic quantum critical endpoint: Application to CeRu2Si2

TL;DR

This paper identifies universal thermodynamic signatures of the metamagnetic quantum critical endpoint, emphasizing the role of diverging susceptibility and Ising symmetry, with experimental illustration in CeRu2Si2.

Contribution

It demonstrates that certain thermodynamic signatures are universal near the metamagnetic quantum critical endpoint, regardless of microscopic details, and relates these to experimental observations in CeRu2Si2.

Findings

Diverging differential susceptibility at the critical endpoint.

Correspondence between susceptibility, magnetostriction, and compressibility.

Sign change in thermal expansion and a minimum in specific heat coefficient.

Abstract

A quantum critical endpoint related to a metamagnetic transition causes distinct signatures in the thermodynamic quantities of a compound. We argue that, irrespective of the microscopic details of the considered material, the diverging differential susceptibility combined with the Ising symmetry of the endpoint give rise to a number of characteristic metamagnetic phenomena. In the presence of a magnetoelastic coupling, one finds a correspondence of susceptibility, magnetostriction and compressibility and, as a result, a pronounced crystal softening, a diverging Grueneisen parameter, a sign change of thermal expansion alpha(H), and a minimum in the specific heat coefficient gamma(H). We illustrate these signatures and their relation on the metamagnetic crossover at 8 T in the prototypical heavy-fermion system CeRu2Si2.