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arXiv · 0809.2887

Uncovering the hidden order in URu2Si2: Identification of Fermi surface instability and gapping

S. Elgazzar·J. Rusz·M. Amft·P. M. Oppeneer·J. A. Mydosh
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Abstract

Spontaneous, collective ordering of electronic degrees of freedom leads to second-order phase transitions that are characterized by an order parameter. The notion "hidden order" (HO) has recently been used for a variety of materials where a clear phase transition occurs to a phase without a known order parameter. The prototype example is the heavy-fermion compound URu2Si2 where a mysterious HO transition occurs at 17.5K. For more than twenty years this system has been studied theoretically and experimentally without a firm grasp of the underlying physics. Using state-of-the-art density-functional theory calculations, we provide here a microscopic explanation for the HO. We identify the Fermi surface "hot spots" where degeneracy induces a Fermi surface instability and quantify how symmetry breaking lifts the degeneracy, causing a surprisingly large Fermi surface gapping. As mechanism for the HO we propose spontaneous symmetry breaking through collective antiferromagnetic moment excitations.

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S. Elgazzar, J. Rusz, M. Amft, P. M. Oppeneer, J. A. Mydosh. 2008-09-17. Uncovering the hidden order in URu2Si2: Identification of Fermi surface instability and gapping. https://arxiv.org/abs/0809.2887

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