Pressure dependence of magnetic transitions in URu₂Si₂
Résumé
Neutron-scattering and specific-heat measurements of the heavy-fermion superconductor URu2Si2 under hydrostatic pressure and with Rh-doping U(Ru0.98Rh0.02)2Si2 show the existence of two magnetic phase transitions: a second-order phase transition with a tiny ordered moment and a first-order phase transition which gives rise to a large moment. The results can be understood in terms of a hidden order parameter ψ linearly coupled to the dipolar ordered moment m.