Hidden Order, Superconductivity and Magnetism in URu2Si2
Date: Thursday, October 15
Place: SST 106
Time: 3:10 pm
Speaker: Prof. John A. Mydosh (Kamerlingh Onnes Laboratory, Univ. of Leiden, The Netherlands)
Title: Hidden Order, Superconductivity and Magnetism in URu2Si2
Abstract: URu2Si2 is a heavy Fermi liquid that possesses exotic ground states. At 17.5 K a unique second-order phase transition occurs that is neither magnetic nor translational, since this transition is at present unexplained it is called hidden order (HO). Only within the HO state an unconventional superconductor is formed at 1.5 K. Moderate pressure can generate a large moment antiferromagnetic (LMAF) phase via a first order phase
transition: HO to LMAF. After 30 years of efforts and ca.
1000 publications, more than 30 different theoretical models have thus far failed to describe the HO state. The mystery of HO has stimulated enormous experiment interest with just about every available condensed matter technique being applied to URu2Si2 and its HO development. We first review the basic bulk properties and electronic structure characteristics of HO and why their behavior is so challenging. To conclude we select three recent experimental methods (neutron scattering, Raman spectroscopy and high magnetic fields) to give us some insights into the HO and possible theoretical modelling.