Evolution of Superconducting and Hidden Order Phases in URu2Si2 Under Applied Pressure

Abstract

AbstractElectrical resistivity measurements performed under applied hydrostatic pressure and in magnetic fields have been used to probe the hidden order (HO) and superconducting (SC) states of URu2Si2, which have ambient-pressure transition temperatures TO = 17.5 K and Tc = 1.5 K, respectively. TO increases with applied pressure and a distinct kink in its pressure dependence is observed at 15 kbar; this feature is associated with the onset of antiferromagnetism. The pressure dependence of the SC upper critical field has been measured with the external field aligned parallel to both crystalline axes. The SC phase is smoothly suppressed to a critical pressure of about 15 kbar and no qualitative change in the critical field curves is observed. The co-evolution of the HO and SC phases is discussed within the context of a model in which the two phases compete for Fermi surface fraction.