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Continuous and discontinuous quantum phase transitions in a model two-dimensional magnet

Haravifard, S. and Banerjee, A. and Lang, J. C. and Srajer, G. and Silevitch, D. M. and Gaulin, B. D. and Dabkowska, H. A. and Rosenbaum, T. F. (2012) Continuous and discontinuous quantum phase transitions in a model two-dimensional magnet. Proceedings of the National Academy of Sciences of the United States of America, 109 (7). pp. 2286-2289. ISSN 0027-8424. PMCID PMC3289308. doi:10.1073/pnas.1114464109.

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The Shasty-Sutherland model, which consists of a set of spin 1/2 dimers on a 2D square lattice, is simple and soluble but captures a central theme of condensed matter physics by sitting precariously on the quantum edge between isolated, gapped excitations and collective, ordered ground states. We compress the model Shastry-Sutherland material, SrCu_2(BO_3)_2, in a diamond anvil cell at cryogenic temperatures to continuously tune the coupling energies and induce changes in state. High-resolution X-ray measurements exploit what emerges as a remarkably strong spin-lattice coupling to both monitor the magnetic behavior and the absence or presence of structural discontinuities. In the low-pressure spin-singlet regime, the onset of magnetism results in an expansion of the lattice with decreasing temperature, which permits a determination of the pressure-dependent energy gap and the almost isotropic spin-lattice coupling energies. The singlet-triplet gap energy is suppressed continuously with increasing pressure, vanishing completely by 2 GPa. This continuous quantum phase transition is followed by a structural distortion at higher pressure.

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Silevitch, D. M.0000-0002-6347-3513
Additional Information:Copyright © 2012 National Academy of Sciences. Edited by Bertrand I. Halperin, Harvard University, Cambridge, MA, and approved December 22, 2011 (received for review September 2, 2011). Published ahead of print January 30, 2012. We are grateful to Y. Feng for helpful discussions. The work at the University of Chicago was supported by National Science Foundation (NSF) Grant DMR-0907025. D.M.S. acknowledges support from US Department of Energy (DOE), Basic Energy Sciences Grant DEFG02-99ER45789. Use of APS is supported by the US DOE Office of Basic Energy Sciences. Author contributions: S.H. and T.F.R. designed research; S.H., B.D.G., and H.A.D. grew samples; S.H., A.B., J.C.L, and G.S. performed research; S.H., A.B., D.M.S., and T.F.R. analyzed data; and S.H., A.B., D.M.S., and T.F.R. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.
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Department of Energy (DOE)DEFG02-99ER45789
Issue or Number:7
PubMed Central ID:PMC3289308
Record Number:CaltechAUTHORS:20140707-163024874
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Official Citation:S. Haravifard, A. Banerjee, J. C. Lang, G. Srajer, D. M. Silevitch, B. D. Gaulin, H. A. Dabkowska, and T. F. Rosenbaum Continuous and discontinuous quantum phase transitions in a model two-dimensional magnet PNAS 2012 109 (7) 2286-2289; published ahead of print January 30, 2012, doi:10.1073/pnas.1114464109
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46925
Deposited By: George Porter
Deposited On:09 Jul 2014 15:43
Last Modified:10 Nov 2021 17:31

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