Quantum geometric effect on Fulde-Ferrell-Larkin-Ovchinnikov superconductivity
Quantum geometric effect on Fulde-Ferrell-Larkin-Ovchinnikov superconductivity
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DOI：
10.1103/physrevb.106.184507
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发表时间：
2022-06
影响因子：
3.7
通讯作者：
Taisei Kitamura;A. Daido;Y. Yanase
中科院分区：
文献类型：
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作者：
Taisei Kitamura;A. Daido;Y. Yanase
量子几何表征了Bloch电子在波空间中的几何性质，由量子度规和Berry曲率表示。最近的研究表明，量子几何在从多极到非厄米物理的各种物理现象中扮演着重要的角色。对于超导体，量子几何被解释为出现在超量子重量(Superfiuidfl)中，这是超导电性的一个基本量。虽然长期以来，超fl的uid重量一直被认为是由费米液体的贡献决定的，但在某些超导体中，如Arti-fi-fl带状体系和单层FeSe，几何贡献是不可忽略的。虽然超级fl的uid重量对于许多与库珀对质心动量有关的超导现象是必不可少的，但量子几何效应对超导电性的全部范围的影响仍然没有得到解决。本文研究了Fulde-Ferrell-Larkin-Ovchinnikov态在平衡状态下获得finite CMMCP的量子几何效应。作为基准，计算了面内磁fi场中单层FeSe的有效模型相图。在各向同性S波对的情况下，量子几何稳定了BCS态，在高磁fi区出现了亚稳态。此外，随着温度的升高，量子几何结构导致了从FFLO态到BCS态的相变。另一方面，对于子格间配对，量子几何对超fl的uid重量有负的贡献，这可以在特定的参数集下诱导出fflo超导电性。
Quantum geometry characterizes the geometric properties of Bloch electrons in the wave space, represented by the quantum metric and the Berry curvature. Recent studies have revealed that the quantum geometry plays a major role in various physical phenomena, from multipole to non-Hermitian physics. For superconductors, the quantum geometry is clarified to appear in the superfluid weight, an essential quantity of superconductivity. Although the superfluid weight was considered to be determined by the Fermi-liquid contribution for a long time, the geometric contribution is not negligible in some superconductors such as artificial flat-band systems and monolayer FeSe. While the superfluid weight is essential for many superconducting phenomena related to the center of mass momenta of Cooper pairs (CMMCP), the full scope of the quantum geometric effect on superconductivity remains unresolved. In this paper, we study the quantum geometric effect on the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state acquiring a finite CMMCP in equilibrium. As a benchmark, the phase diagrams of effective models for monolayer FeSe in an in-plane magnetic field are calculated. In the case of the isotropic s -wave pairing, the quantum geometry stabilizes the BCS state, and a metastable BCS state appears in the high magnetic field region. In addition, the quantum geometry induces the phase transition from the FFLO state to the BCS state with increasing temperature. On the other hand, for the inter-sublattice pairing, the quantum geometry gives a negative contribution to the superfluid weight; this can induce the FFLO superconductivity in particular parameter sets.