On the destruction of the hidden order in URu$_2$Si$_2$ by a strong magnetic field

TL;DR

This study investigates how strong magnetic fields suppress the hidden order in URu$_2$Si$_2$, revealing a Fermi surface reconstruction and a transition to a polarized heavy fermion metal with reduced effective mass.

Contribution

It provides detailed transport measurements showing the destruction of hidden order and the emergence of a polarized heavy fermion state under high magnetic fields.

Findings

Nernst response suppressed above 35 T

Fermi surface reconstructed in high fields

Transition to polarized heavy fermions with reduced effective mass

Abstract

We present a study of transport properties of the heavy fermion URu$_2$Si$_2$ in pulsed magnetic field. The large Nernst response of the hidden order state is found to be suppressed when the magnetic field exceeds 35 T. The combination of resistivity, Hall and Nernst data outlines the reconstruction of the Fermi surface in the temperature-field phase diagram. The zero-field ground state is a compensated heavy-electron semi-metal, which is destroyed by magnetic field through a cascade of field-induced transitions. Above 40 T, URu$_2$Si$_2$ appears to be a polarized heavy fermions metal with a large density of carriers whose effective mass rapidly decreases with increasing magnetic polarization.