We report 29Si NMR measurements in single crystals and aligned powders of URu2Si2 in the hidden order and paramagnetic phases. The spin-lattice-relaxation data reveal evidence of pseudospin fluctuations of U moments in the paramagnetic phase. We find evidence for partial suppression of the density of states below 30 K, and analyze the data in terms of a two component spin-fermion model. We propose that this behavior is a realization of a pseudogap between the hidden order transition THO and 30 K. This behavior is then compared to other materials that demonstrate precursor fluctuations in a pseudogap regime above a ground state with long-range order.
@article{arxiv.1311.3289,
title = {Nuclear magnetic resonance studies of pseudospin fluctuations in URu$_2$Si$_2$},
author = {K. R. Shirer and J. T. Haraldsen and A. P. Dioguardi and J. Crocker and N. apRoberts-Warren and A. C. Shockley and C. -H. Lin and D. M. Nisson and J. C. Cooley and M. Janoschek and K. Huang and N. Kanchanavatee and M. B. Maple and M. J. Graf and A. V. Balatsky and N. J. Curro},
journal= {arXiv preprint arXiv:1311.3289},
year = {2013}
}