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

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 $\gtrsim 1$~T for $\mathbf{H}\parallel \mathbf{a}$ and in fields higher than $\gtrsim 20$~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.

9 pages, 5 figures + Supplemental Material (6 pages, 7 figures)