Abstract
We propose a candidate for the hidden order in URuSi: a rank-5 type spin-density wave between uranium crystal-field doublets and , breaking time-reversal and lattice tetragonal symmetry in a manner consistent with recent torque measurements [Okazaki et al., Science 331, 439 (2011)]. We argue that coupling of this order parameter to magnetic probes can be hidden by crystal-field effects, while still having significant effects on transport, thermodynamics, and magnetic susceptibilities. In a simple tight-binding model for the heavy quasiparticles, we show the connection between the hidden order and antiferromagnetic phases arises since they form different components of this single rank-5 pseudospin vector. Using a phenomenological theory, we show that the experimental pressure-temperature phase diagram can be qualitatively reproduced by tuning terms which break pseudospin rotational symmetry. As a test of our proposal, we predict the presence of small magnetic moments in the basal plane oriented in the direction ordered at the wave vector .
- Received 12 March 2012
DOI:https://doi.org/10.1103/PhysRevB.85.245112
©2012 American Physical Society