Publication Date:
2016-07-16
Description:
Author(s): C. H. Booth, S. A. Medling, J. G. Tobin, R. E. Baumbach, E. D. Bauer, D. Sokaras, D. Nordlund, and T.-C. Weng URu 2 Si 2 undergoes a second-order phase transition at 17.5 K that has defied attempts to identify its order parameter despite a vast literature extending over the last 30 years. A wide variety of theories have been posed to explain this so-called “hidden order”, some with exotic ground states. An important dividing line between these theories is the character of the 5 f orbital: on one side sit theories that require a localized f 2 configuration ( f -manifold crystalline electric field effects, hastatic order, etc.), while on the other sit those that start from an itinerant, partially occupied f 3 orbital (band structure + hybridization). Unfortunately, the experimental measures remain muddy on this issue, with indications of both localized f 2 and itinerant f 3 behavior depending on the experiment. Here, the authors report U L I I I -edge absorption/ L α 1 emission resonant x-ray emission spectroscopy measurements comparing data from URu 2 Si 2 to UCd 11 , UF 4 , and UO 2 data to unravel the various roles of f -orbital occupation, delocalization, and ligand-field splitting of the d manifold. The data indicate a dominant delocalized f 3 configuration that is likely partially occupied, with no measurable change in occupancy to temperatures as low as 10 K. While these measurements do not rule out a minority localized f 2 configuration, any theory relying on such a configuration must account for its relatively small contribution to the Fermi surface. [Phys. Rev. B 94, 045121] Published Fri Jul 15, 2016
Keywords:
Electronic structure and strongly correlated systems
Print ISSN:
1098-0121
Electronic ISSN:
1095-3795
Topics:
Physics
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