Is the optical conductivity of heavy fermion strange metals Planckian?
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1.
California Institute of Technology
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2.
Rice University
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3.
TU Wien
Abstract
Strange metal behavior appears across a variety of condensed matter settings and beyond, and achieving a universal understanding is an exciting prospect. The beyond-Landau quantum criticality of Kondo destruction has had considerable success in describing the behavior of strange metal heavy fermion compounds, and there is some evidence that the associated partial localization-delocalization nature can be generalized to diverse materials classes. Other potential overarching principles at play are also being explored. An intriguing proposal is that Planckian scattering, with a rate of kBT/ℏ, leads to the linear temperature dependence of the (dc) electrical resistivity, which is a hallmark of strange metal behavior. Here we extend a previously introduced analysis scheme based on the Drude description of the dc resistivity to optical conductivity data. When they are well described by a simple (ac) Drude model, the scattering rate can be directly extracted. This avoids the need to determine the ratio of charge carrier concentration to effective mass, which has complicated previous analyses based on the dc resistivity. However, we point out that strange metals typically exhibit strong deviations from Drude behavior, as exemplified by the “extreme” strange metal YbRh2Si2. This calls for alternative approaches, and we point to the power of strange metal dynamical (energy-over-temperature) scaling analyses for the inelastic part of the optical conductivity. If such scaling extends to the low-frequency limit, a strange metal relaxation rate can be estimated, and may ultimately be used to test whether strange metals relax in a Planckian manner.
Copyright and License
© 2023 Li, Kono, Si and Paschen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Acknowledgement
We acknowledge fruitful discussions with Peter Armitage, Antoine Georges, Patrick Lee, Subir Sachdev, Marc Scheffler, T. Senthil, Mathieu Taupin, and Eric van Heumen.
Funding
XL acknowledges support from the Caltech Postdoctoral Prize Fellowship and the IQIM. JK acknowledges support from the Robert A. Welch Foundation through Grant No. C-1509. The work of QS is supported primarily by the Air Force Office of Scientific Research under Grant No. FA9550-21-1–0356, the National Science Foundation Grant No. DMR-2220603 and the Robert A. Welch Foundation under Grant No. C-1411. SP acknowledges funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement no 824109 and from the Austrian Science Fund (FWF Grants 29296-N27 and I5868-N–FOR 5249 - QUAST). SP and QS acknowledge the hospitality of the Aspen Center for Physics, which is supported by NSF grant No. PHY-1607611.
Contributions
XL performed the Drude and scaling analyses, SP conceived the work and wrote the paper, with input from XL, JK, and QS. All authors contributed to the discussion.
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Additional details
Identifiers
Related works
- Is new version of
- Discussion Paper: arXiv:2205.13382 (arXiv)
Funding
- Caltech Postdoctoral Fellowship
- Institute for Quantum Information and Matter (IQIM)
- Robert A. Welch Foundation
- C-1509
- Air Force Office of Scientific Research (AFOSR)
- FA9550-21-1-0356
- National Science Foundation
- DMR-2220603
- Robert A. Welch Foundation
- C-1411
- European Research Council (ERC)
- 824109
- FWF Der Wissenschaftsfonds
- 29296-N27
- FWF Der Wissenschaftsfonds
- I5868-N–FOR 5249
- National Science Foundation
- PHY-1607611
Dates
- Submitted
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2022-05-02
- Accepted
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2022-12-28
Caltech Custom Metadata
- Caltech groups
- Institute for Quantum Information and Matter
- Publication Status
- Published