Criticalities in the itinerant ferromagnet UGe$_{2}$

TL;DR

This paper offers a detailed microscopic model of UGe$_{2}$, explaining its classical and quantum critical magnetic behaviors and predicting the evolution of critical points under varying conditions.

Contribution

It provides a comprehensive microscopic description of all critical points in UGe$_{2}$, matching experimental data and predicting quantum criticality emergence.

Findings

Quantitative agreement with experimental critical points.

Prediction of quantum critical point at zero temperature.

Identification of Fermi surface topology influence on critical behavior.

Abstract

We provide a microscopic description of the magnetic properties of UGe$_2$ and in particular, of its both classical and quantum critical behavior. Namely, we account for all the critical points: the critical ending point (CEP) at the metamagnetic phase transition, the tricritical point, and the quantum critical end point at the ferromagnetic to paramagnetic phase transition. Their position agrees quantitatively with experiment. Additionally, we predict that the metamagnetic CEP can be traced down to zero temperature and becomes quantum critical point by a small decrease of both the total electron concentration and the external pressure. The system properties are then determined by the quantum critical fluctuations appearing near the instability point of the Fermi surface topology.