Anisotropic collapse of electronic correlations in the ferromagnet UGe$_2$ under high magnetic field

TL;DR

This study investigates how high magnetic fields anisotropically suppress electronic correlations in the heavy-fermion ferromagnet UGe₂, revealing directional dependence in resistivity, ferromagnetic stability, and Fermi surface properties.

Contribution

It provides the first detailed analysis of anisotropic electronic correlation suppression and Fermi surface behavior in UGe₂ under high magnetic fields.

Findings

Resistivity decreases significantly when magnetic field is along the easy axis

The Curie temperature anomaly disappears at different fields depending on the field direction

Quantum oscillations indicate a two-dimensional Fermi surface at high fields

Abstract

We present electrical-resistivity measurements on the prototypical heavy-fermion ferromagnet UGe$_2$ under pulsed magnetic field up to 60~T. An anisotropic field-induced suppression of the electronic correlations is revealed. The electrical resistivity strongly decreases when a magnetic field $\mathbf{H}$ is applied along the easy magnetic axis $\mathbf{a}$, while it remains almost unchanged when $\mathbf{H}$ is applied along the hard magnetic axes $\mathbf{b}$ and $\mathbf{c}$. The field-induced destabilization of the ferromagnetic state is also anisotropic: the anomaly at the Curie temperature $T_C$ disappears in fields higher than $\gtrsim1$~T for $\mathbf{H}\parallel\mathbf{a}$ and in fields higher than $\gtrsim20$~T for $\mathbf{H}\parallel\mathbf{b},\mathbf{c}$. At temperatures below 2~K, we observe quantum oscillations in fields larger than 50~T applied along $\mathbf{b}$, which support the presence of a two-dimensional Fermi surface similar to that previously observed at low fields.