On the destruction of the hidden order in URu₂Si₂ by a strong magnetic field

¹  Laboratoire National des Champs Magnétiques Pulsés (UMR 5147 CNRS-UPS-INSA) - Toulouse, France, EU
²  Laboratoire Photons et Matière (UPR5-CNRS), ESPCI - 10 Rue de Vauquelin, 75231 Paris, France, EU
³  Institut Nanosciences et Cryogénie, SPSMS/MDN, CEA-Grenoble - 38054 Grenoble, France, EU
⁴  Institut Néel, CNRS/UJF, B.P. 166, 38 042 Grenoble Cedex 9, France, EU

Corresponding author: proust@lncmp.org

Received: 26 September 2008
Accepted: 11 December 2008

Abstract

We present a study of the transport properties of the heavy-fermion URu₂Si₂ 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, URu₂Si₂ appears to be a polarized heavy-fermions metal with a large density of carriers whose effective mass rapidly decreases with increasing magnetic polarization.