Hidden order in URu2Si2
Abstract
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. At Tm∼17.5 K, a second-order phase transition with strong anomalies in the specific heat and other macroscopic and transport properties are accompanied by an antiferromagnetically ordered dipolar moment of only 0.03μB. At TM<Tm under pressure, p⩾5 kbar, or small Rh doping, a first-order phase transition gives rise to small anomalies in the specific heat and a large ordered moment of ∼0.3μB, but with the same magnetic structure. The results can be understood in terms of a hidden order parameter ψ, which is linearly coupled to the ordered moment m. It follows that m and ψ have the same symmetry and hence both break time-reversal symmetry.
- Publication:
-
Physica B Condensed Matter
- Pub Date:
- April 2005
- DOI:
- 10.1016/j.physb.2005.01.318
- Bibcode:
- 2005PhyB..359..986B