Abstract
Abstract
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
c
′
<
T
c
. At the first stage,
T
c
′
<
T
<
T
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
c
′
, 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.
Funder
Strategic Priority Research Program of Chinese Academy of Sciences
National Natural Science Foundation of China
China Postdoctoral Science Foundation
K C Wong Education Foundation
Subject
General Physics and Astronomy
Cited by
7 articles.
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