Two-stage superconductivity in the Hatsugai–Kohomoto-BCS model
Superconductivity in strongly correlated electrons can emerge out from a normal state that is beyond the Landau’s Fermi liquid paradigm, often dubbed as ‘non-Fermi liquid’. While the theory for non-Fermi liquid is still not yet conclusive, a recent study on the exactly-solvable Hatsugai–Kohomoto (HK...
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IOP Publishing
2022-01-01
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Online Access: | https://doi.org/10.1088/1367-2630/ac9548 |
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author | Yu Li Vivek Mishra Yi Zhou Fu-Chun Zhang |
author_facet | Yu Li Vivek Mishra Yi Zhou Fu-Chun Zhang |
author_sort | Yu Li |
collection | DOAJ |
description | Superconductivity in strongly correlated electrons can emerge out from a normal state that is beyond the Landau’s Fermi liquid paradigm, often dubbed as ‘non-Fermi liquid’. While the theory for non-Fermi liquid is still not yet conclusive, a recent study on the exactly-solvable Hatsugai–Kohomoto (HK) model has suggested a non-Fermi liquid ground state whose Green’s function resembles the Yang–Rice–Zhang ansatz for cuprates (2020 Phillips et al Nat. Phys. 16 1175). Similar to the effect of on-site Coulomb repulsion in the Hubbard model, the repulsive interaction in the HK model divides the momentum space into three parts: empty, single-occupied and double-occupied regions, that are separated from each other by two distinct Fermi surfaces. In the presence of an additional Bardeen–Cooper–Schrieffer-type pairing interaction of a moderate strength, we show that the system exhibits a ‘two-stage superconductivity’ feature as temperature decreases: a first-order superconducting transition occurs at a temperature T _c that is followed by a sudden increase of the superconducting order parameter at a lower temperature ${T}_{\text{c}}^{\prime }< {T}_{\text{c}}$ . At the first stage, ${T}_{\text{c}}^{\prime }< T< {T}_{\text{c}}$ , the pairing function arises and the entropy is released only in the vicinity of the two Fermi surfaces; while at the second stage, $T< {T}_{\text{c}}^{\prime }$ , the pairing function becomes significant and the entropy is further released in deep (single-occupied) region in the Fermi sea. The phase transitions are analyzed within the Ginzburg–Landau theory. Our work sheds new light on unconventional superconductivity in strongly correlated electrons. |
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spelling | doaj.art-08c1d5f8b1294f738c92eefcf973fd3f2023-08-09T14:25:11ZengIOP PublishingNew Journal of Physics1367-26302022-01-01241010301910.1088/1367-2630/ac9548Two-stage superconductivity in the Hatsugai–Kohomoto-BCS modelYu Li0https://orcid.org/0000-0003-0813-8517Vivek Mishra1https://orcid.org/0000-0003-2971-8764Yi Zhou2Fu-Chun Zhang3Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences , Beijing 100190, People’s Republic of ChinaKavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences , Beijing 100190, People’s Republic of ChinaBeijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences , Beijing 100190, People’s Republic of China; Songshan Lake Materials Laboratory , Dongguan, Guangdong 523808, People’s Republic of China; CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences , Beijing 100190, People’s Republic of ChinaKavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences , Beijing 100190, People’s Republic of China; CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences , Beijing 100190, People’s Republic of ChinaSuperconductivity in strongly correlated electrons can emerge out from a normal state that is beyond the Landau’s Fermi liquid paradigm, often dubbed as ‘non-Fermi liquid’. While the theory for non-Fermi liquid is still not yet conclusive, a recent study on the exactly-solvable Hatsugai–Kohomoto (HK) model has suggested a non-Fermi liquid ground state whose Green’s function resembles the Yang–Rice–Zhang ansatz for cuprates (2020 Phillips et al Nat. Phys. 16 1175). Similar to the effect of on-site Coulomb repulsion in the Hubbard model, the repulsive interaction in the HK model divides the momentum space into three parts: empty, single-occupied and double-occupied regions, that are separated from each other by two distinct Fermi surfaces. In the presence of an additional Bardeen–Cooper–Schrieffer-type pairing interaction of a moderate strength, we show that the system exhibits a ‘two-stage superconductivity’ feature as temperature decreases: a first-order superconducting transition occurs at a temperature T _c that is followed by a sudden increase of the superconducting order parameter at a lower temperature ${T}_{\text{c}}^{\prime }< {T}_{\text{c}}$ . At the first stage, ${T}_{\text{c}}^{\prime }< T< {T}_{\text{c}}$ , the pairing function arises and the entropy is released only in the vicinity of the two Fermi surfaces; while at the second stage, $T< {T}_{\text{c}}^{\prime }$ , the pairing function becomes significant and the entropy is further released in deep (single-occupied) region in the Fermi sea. The phase transitions are analyzed within the Ginzburg–Landau theory. Our work sheds new light on unconventional superconductivity in strongly correlated electrons.https://doi.org/10.1088/1367-2630/ac9548strongly-correlated systemunconventional superconductivitynon-Fermi liquidGinzburg–Landau theory |
spellingShingle | Yu Li Vivek Mishra Yi Zhou Fu-Chun Zhang Two-stage superconductivity in the Hatsugai–Kohomoto-BCS model New Journal of Physics strongly-correlated system unconventional superconductivity non-Fermi liquid Ginzburg–Landau theory |
title | Two-stage superconductivity in the Hatsugai–Kohomoto-BCS model |
title_full | Two-stage superconductivity in the Hatsugai–Kohomoto-BCS model |
title_fullStr | Two-stage superconductivity in the Hatsugai–Kohomoto-BCS model |
title_full_unstemmed | Two-stage superconductivity in the Hatsugai–Kohomoto-BCS model |
title_short | Two-stage superconductivity in the Hatsugai–Kohomoto-BCS model |
title_sort | two stage superconductivity in the hatsugai kohomoto bcs model |
topic | strongly-correlated system unconventional superconductivity non-Fermi liquid Ginzburg–Landau theory |
url | https://doi.org/10.1088/1367-2630/ac9548 |
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