Quantum Critical Metals: From Loss of Quasiparticles to High-Tc Superconductivity
ORAL · Invited
Abstract
Strange metals develop near quantum critical points in a variety of correlated systems. Some of the key issues include how the quantum critical state loses quasiparticles, how it drives superconductivity, and to what extent the strange-metal physics in different classes of correlated systems is connected with each other.
In this talk, I will confront some of these issues from the vantage point of heavy fermion metals, which represent a prototype family for quantum critical metals and strange-metal phenomena. I will describe the notion of Kondo destruction [1] and how it leads to a change of the Fermi surface from “large” to “small” across the quantum critical point, a loss of quasiparticles everywhere on the Fermi surface at the quantum critical point, and a dynamical Planckian scaling in various properties including the charge responses [2]. I will then present results showing that such a strange-metal state drives unconventional superconductivity with high-Tc: the transition temperature Tc reaches a few percent of the effective Fermi temperature [3].
Connections with other correlated systems – including the cuprates, moir structures and in particular frustrated bulk systems with topological “flat bands” [4] -- will be briefly discussed.
In collaboration with A. Cai, L. Chen, L. Y. Chen, K. Grube, H. Hu, K. Ingersent, A. Kandala, S. Kirchner, J. Kono, X. Li, C.-C. Liu, D. Natelson, E. M. Nica, J. Pixley, S. Paschen, L. Prochaska, C. Setty, F. Steglich, S. Sur, J. D. Thompson, H. von Lhneysen, Y. Wang, S. Wirth, F. Xie, R. Yu and J.-X. Zhu.
In this talk, I will confront some of these issues from the vantage point of heavy fermion metals, which represent a prototype family for quantum critical metals and strange-metal phenomena. I will describe the notion of Kondo destruction [1] and how it leads to a change of the Fermi surface from “large” to “small” across the quantum critical point, a loss of quasiparticles everywhere on the Fermi surface at the quantum critical point, and a dynamical Planckian scaling in various properties including the charge responses [2]. I will then present results showing that such a strange-metal state drives unconventional superconductivity with high-Tc: the transition temperature Tc reaches a few percent of the effective Fermi temperature [3].
Connections with other correlated systems – including the cuprates, moir structures and in particular frustrated bulk systems with topological “flat bands” [4] -- will be briefly discussed.
In collaboration with A. Cai, L. Chen, L. Y. Chen, K. Grube, H. Hu, K. Ingersent, A. Kandala, S. Kirchner, J. Kono, X. Li, C.-C. Liu, D. Natelson, E. M. Nica, J. Pixley, S. Paschen, L. Prochaska, C. Setty, F. Steglich, S. Sur, J. D. Thompson, H. von Lhneysen, Y. Wang, S. Wirth, F. Xie, R. Yu and J.-X. Zhu.
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Publication: [1] Q. Si et al., Nature 413, 804 (2001); S. Paschen & Q. Si, Nat. Rev. Phys. 3, 9 (2021); S. Kirchner et al, RMP 92, 011002 (2020).<br><br>[2] A. Kandala et al., arXiv:2206.01174. A. Cai et al., PRL 124, 027205 (2020); L. Prochaska et al., Science 367, 285 (2020).<br><br>[3] H. Hu et al., arXiv:2109.13224.<br><br>[4] H. Hu & Q. Si, arXiv:2209.10396.
Presenters
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Qimiao Si
Rice University
Authors
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Qimiao Si
Rice University