Solvable model for a charge- 4e superconductor
Solvable model for a charge- 4e superconductor
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DOI：
10.1103/physrevb.106.094508
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发表时间：
2021-11
影响因子：
3.7
通讯作者：
N. V. Gnezdilov;Yuxuan Wang
中科院分区：
文献类型：
--
作者：
N. V. Gnezdilov;Yuxuan Wang
电荷-$4E$超导体是由四重态电子凝聚而成的。虽然前人的工作是从非常规超导体中库珀对的束缚来分析电荷-4E超导电性的形成机制，但由于其内在的相互作用性质，即使在平均场水平上也没有系统地研究它在费米区的性质。在这里，我们提出了一个带电超导体的可解模型--带有反常四次项的Sachdev-Ye-Kitaev模型的自旋版本。我们发现基态是无隙的，类似于重的费米液体。我们对超流密度进行了解析求解，结果表明，超流密度在电荷-4E序参数的强度上是微扰的，这与常规(电荷-2E)超导体形成鲜明对比。在降低温度下，我们发现电荷-4E$有序与规则相互作用项之间的关联可以驱动一级相变到电荷-2E$超导态。
A charge-$4e$ superconductor forms due to the condensation of quartets of electrons. While in previous works the mechanism for the formation of charge-$4e$ superconductivity has been analyzed in terms of the binding of Cooper pairs in unconventional superconductors, its properties in the fermionic sector have not been studied systematically due to its inherently interacting nature even at the mean-field level. Here we propose a solvable model for a charge-$4e$ superconductor -- a spinful version of the Sachdev-Ye-Kitaev model with an anomalous quartic term. We show that the ground state is gapless and resembles a heavy Fermi liquid. We analytically solve for the superfluid density and show that it is perturbative in the strength of the charge-$4e$ order parameter, in sharp contrast with a regular (charge-$2e$) superconductor. Upon lowering temperature, we show that the correlation between charge-$4e$ order and regular interaction terms can drive a first-order phase transition to a charge-$2e$ superconducting state.