Candidate Elastic Quantum Critical Point in LaCu6-xAux

L. Poudel, A. F. May, M. R. Koehler, M. A. McGuire, S. Mukhopadhyay, S. Calder, R. E. Baumbach, R. Mukherjee, D. Sapkota, C. De La Cruz, D. J. Singh, D. Mandrus, A. D. Christianson

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13 Scopus citations

Abstract

The structural properties of LaCu6-xAux are studied using neutron diffraction, x-ray diffraction, and heat capacity measurements. The continuous orthorhombic-monoclinic structural phase transition in LaCu6 is suppressed linearly with Au substitution until a complete suppression of the structural phase transition occurs at the critical composition xc=0.3. Heat capacity measurements at low temperatures indicate residual structural instability at xc. The instability is ferroelastic in nature, with density functional theory calculations showing negligible coupling to electronic states near the Fermi level. The data and calculations presented here are consistent with the zero temperature termination of a continuous structural phase transition suggesting that the LaCu6-xAux series hosts an elastic quantum critical point.

Original languageEnglish
Article number235701
JournalPhysical Review Letters
Volume117
Issue number23
DOIs
StatePublished - Nov 30 2016

Funding

We acknowledge V. Keppens, V. Fanelli, T. Williams, and P. Whitfield for useful discussions, F. Ye for help with sample characterization, and M. Suchomel for assistance with the synchrotron x-ray measurements. The research at the High Flux Isotope Reactor (ORNL) is supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy (DOE). Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A.F.M., M.A.M., S.M., and D.M. acknowledge the support of the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Work at the University of Missouri was supported by DOE through the S3TEC Energy Frontier Research Center Award No.DE-SC0001299/DE-FG02-09ER46577. Work performed at the National High Magnetic Field Laboratory is supported by National Science Foundation (NSF) Cooperative Agreement No.DMR-1157490, the State of Florida, and the U.S. Department of Energy (DOE NNSA DE-NA0001979).

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