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Singular charge fluctuations at a magnetic quantum critical point

Prochaska, L. and Li, X. and MacFarland, D. C. and Andrews, A. M. and Bonta, M. and Bianco, E. F. and Yazdi, S. and Schrenk, W. and Detz, H. and Limbeck, A. and Si, Q. and Ringe, E. and Strasser, G. and Kono, J. and Paschen, S. (2020) Singular charge fluctuations at a magnetic quantum critical point. Science, 367 (6475). pp. 285-288. ISSN 0036-8075.

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Strange metal behavior is ubiquitous in correlated materials, ranging from cuprate superconductors to bilayer graphene, and may arise from physics beyond the quantum fluctuations of a Landau order parameter. In quantum-critical heavy-fermion antiferromagnets, such physics may be realized as critical Kondo entanglement of spin and charge and probed with optical conductivity. We present terahertz time-domain transmission spectroscopy on molecular beam epitaxy–grown thin films of YbRh₂Si₂, a model strange-metal compound. We observed frequency over temperature scaling of the optical conductivity as a hallmark of beyond-Landau quantum criticality. Our discovery suggests that critical charge fluctuations play a central role in the strange metal behavior, elucidating one of the long-standing mysteries of correlated quantum matter.

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Additional Information:© 2020 American Association for the Advancement of Science. This is an article distributed under the terms of the Science Journals Default License. Received 6 August 2018; resubmitted 7 September 2019. Accepted 5 December 2019. We thank P. Gegenwart, Y.-B. Kim, H. von Löhneysen, S. Nakatsuji, H.-C. Nägerl, and A. Prokofiev for useful discussions. Financial support for this work was provided by the European Research Council (ERC Advanced Grant 227378), the U.S. Army Research Office (ARO W911NF-14-1-0496), the Austrian Science Fund (FWF W1243, P29279-N27, and P29296-N27), and the European Union’s Horizon 2020 research and innovation program (grant agreement 824109-EMP). X.L. and J.K. acknowledge financial support from the National Science Foundation (NSF MRSEC DMR-1720595) and the ARO (W911NF-17-1-0259). Q.S. acknowledges financial support from the NSF (DMR-1920740), the Robert A. Welch Foundation (C-1411), and the ARO (W911NF-14-1-0525) and the hospitality of the University of California at Berkeley, the Aspen Center for Physics (NSF grant PHY-1607611), and the Los Alamos National Laboratory (through a Ulam Scholarship from the Center for Nonlinear Studies). This work has also been supported by an InterDisciplinary Excellence Award (IDEA) from Rice University (Q.S., E.R., J.K., and S.P.). Author contributions: S.P. designed and led the research. L.P., D.C.M., A.M.A., W.S., H.D., and G.S. performed the MBE growth. M.B. and A.L. performed the analytical characterization. E.F.B., S.Y., and E.R. performed the TEM investigation. X.L. and J.K. performed the terahertz spectroscopy. Q.S. contributed to the understanding of the results. L.P., X.L., D.C.M., Q.S., and S.P. wrote the manuscript, with contributions from all other authors. The authors have no competing interests. Data and materials availability: All data presented in this paper are deposited in Zenodo (34).
Group:IQIM, Institute for Quantum Information and Matter
Funding AgencyGrant Number
European Research Council (ERC)227378
Army Research Office (ARO)W911NF-14-1-0496
FWF Der WissenschaftsfondsFWF W1243
FWF Der WissenschaftsfondsP29279-N27
FWF Der WissenschaftsfondsP29296-N27
European Research Council (ERC)824109
Army Research Office (ARO)W911NF-17-1-0259
Robert A. Welch FoundationC-1411
Army Research Office (ARO)W911NF-14-1-0525
Los Alamos National LaboratoryUNSPECIFIED
Rice UniversityUNSPECIFIED
Issue or Number:6475
Record Number:CaltechAUTHORS:20200116-140345082
Persistent URL:
Official Citation:Singular charge fluctuations at a magnetic quantum critical point. L. Prochaska, X. Li, D. C. MacFarland, A. M. Andrews, M. Bonta, E. F. Bianco, S. Yazdi, W. Schrenk, H. Detz, A. Limbeck, Q. Si, E. Ringe, G. Strasser, J. Kono and S. Paschen. Science 367 (6475), 285-288; DOI: 10.1126/science.aag1595
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100766
Deposited By: Tony Diaz
Deposited On:16 Jan 2020 22:26
Last Modified:16 Jan 2020 22:36

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