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Order parameter fluctuations at a buried quantum critical point

Feng, Yejun and Wang, Jiyang and Jaramillo, R. and van Wezel, Jasper and Haravifard, S. and Srajer, G. and Liu, Y. and Xu, Z.-A. and Littlewood, P. B. and Rosenbaum, T. F. (2012) Order parameter fluctuations at a buried quantum critical point. Proceedings of the National Academy of Sciences of the United States of America, 109 (19). pp. 7224-7229. ISSN 0027-8424. PMCID PMC3358829. doi:10.1073/pnas.1202434109.

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Quantum criticality is a central concept in condensed matter physics, but the direct observation of quantum critical fluctuations has remained elusive. Here we present an X-ray diffraction study of the charge density wave (CDW) in 2H-NbSe_2 at high pressure and low temperature, where we observe a broad regime of order parameter fluctuations that are controlled by proximity to a quantum critical point. X-rays can track the CDW despite the fact that the quantum critical regime is shrouded inside a superconducting phase; and in contrast to transport probes, allow direct measurement of the critical fluctuations of the charge order. Concurrent measurements of the crystal lattice point to a critical transition that is continuous in nature. Our results confirm the long-standing expectations of enhanced quantum fluctuations in low-dimensional systems, and may help to constrain theories of the quantum critical Fermi surface.

Item Type:Article
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URLURL TypeDescription CentralArticle
Feng, Yejun0000-0003-3667-056X
Additional Information:© 2012 National Academy of Sciences. Edited by Zachary Fisk, University of California, Irvine, CA, and approved March 9, 2012 (received for review February 9, 2012). Published ahead of print April 23, 2012. We thank X. Lin for help on sample growth. The work at the University of Chicago was supported by National Science Foundation (NSF) Grant DMR-0907025. Use of the Advanced Photon Source and the work at the Materials Science Division of Argonne National Laboratory were supported by the Department of Energy Basic Energy Sciences under Contract NE-AC02-06CH11357. The work at Zhejiang University was supported by NSF of China. Author contributions: Y.F., R.J. and T.F.R. designed research; Y.F., J.W., J.v.W., S.H., G.S., and P.B.L. performed research; Y.L. and Z.-A.X. contributed new reagents/analytic tools; Y.F., R.J., and T.F.R. analyzed data; and Y.F., R.J., J.v.W. and T.F.R. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC02-06CH11357
National Science Foundation of ChinaUNSPECIFIED
Subject Keywords:incommensurate electronic state; transition metal dichalcogenides; diffraction line shapes; diamond anvil cell
Issue or Number:19
PubMed Central ID:PMC3358829
Record Number:CaltechAUTHORS:20140707-163024695
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Official Citation:Yejun Feng, Jiyang Wang, R. Jaramillo, Jasper van Wezel, S. Haravifard, G. Srajer, Y. Liu, Z.-A. Xu, P. B. Littlewood, and T. F. Rosenbaum Order parameter fluctuations at a buried quantum critical point PNAS 2012 109 (19) 7224-7229; published ahead of print April 23, 2012, doi:10.1073/pnas.1202434109
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46924
Deposited By: George Porter
Deposited On:09 Jul 2014 15:13
Last Modified:10 Nov 2021 17:31

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