Field Reentrance of the Hidden Order State of URu₂Si₂ under Pressure

Abstract

Combination of neutron scattering and thermal expansion measurements under\npressure shows that the so-called hidden order phase of URu2Si2 reenters in\nmagnetic field when antiferromagnetism (AF) collapses at H_AF (T). Macroscopic\npressure studies of the HO-AF boundaries were realized at different pressures\nvia thermal expansion measurements under magnetic field using a strain gauge.\nMicroscopic proof at a given pressure is the reappearance of the resonance at\nQ_0=(1,0,0) under field which is correlated with the collapse of the AF Bragg\nreflections at Q_0.\n