Phase diagram of heavy fermion systems

TL;DR

This paper explores the complex phase diagram of heavy fermion systems, focusing on the interplay of valence, electronic structure, and magnetism, using various experimental tools to understand their ground states and quantum critical behavior.

Contribution

It provides a comprehensive analysis of the phase diagram of heavy fermion systems, emphasizing the role of external parameters and the Grüneisen parameter in revealing competing interactions.

Findings

Identification of different ground states in heavy fermion systems.

The Grüneisen parameter as a key indicator of competing hierarchies.

Insights into the transition towards Fermi liquid behavior at low temperatures.

Abstract

The Meccano of heavy fermion systems is shown on different cases going from anomalous monochalcogenides to cerium intermetallic compounds with special focus on the ideal case of the CeRu2Si2 series. Discussion is made in the frame of the interplay between valence, electronic structure (Fermi surface), and magnetism. The nice tools given by the temperature, the pressure, and the magnetic field allow to explore different ground states as well as the slow downhill ''race'' before reaching a Fermi liquid finish line at very low temperature. Experimentally, the Gr"uneisen parameter i.e. the ratio of the thermal expansion by the specific heat is a coloured magic number; its temperature, pressure, and magnetic field dependence is a deep disclosure of competing hierarchies and the conversion of this adaptive matter to external responses.