学术报告（2025年1月14日16:00）：Quantum geometric effects on unconventional superconductivity

主持人：严忠波教授

报告摘要：Quantum geometry governs several important features in superconductivity. In this talk, I will discuss my recent works on this topic. For concreteness, I will talk about (1) Recent experimental study unveiled highly unconventional phenomena in the superconducting twisted bilayer graphene (TBG) with ultra flat bands, which cannot be described by the conventional BCS theory. I will show that the quantum metric, which is the real part of the quantum geometric tensor, gives rise to an anomalous contribution to the coherence length in a superconductor, with a particular application in flat-band systems such as TBG. (2) We propose a new scheme for the FFLO Cooper pairing states within flat bands. Central to our approach is the concept of “quantum geometric discrepancy” that characterizes the discrepancy in the quantum geometry of paired electrons, leading to the flat-band FFLO instability. (3) I will discuss a new nonlinear magnetic response in magnet/superconductor hybrids, which can reveal the quantum geometric effect of the BDG Hamiltonian.

Ref.

[1] Hu, Jin-Xin, et al. "Anomalous coherence length in superconductors with quantum metric." Communication Phys (2024)

[2] Zi-Ting Sun, Hu, Jin-Xin*, et al. "Flat-band Fulde-Ferrell-Larkin-Ovchinnikov State from Quantum Geometry Discrepancy." arXiv preprint arXiv:2408.00548 (2024).

[3] Hu, Jin-Xin, et al. "Nonlinear Superconducting Magnetoelectric Effect." PRL (2024)

报告人简介：胡金鑫，2018年本科毕业于中国科学技术大学物理系，2023年博士毕业于香港科技大学物理系，2023年8月-2024年11月新加坡南洋理工大学做博士后，2024年11至今在香港科技大学做博士后。主要从事转角二维材料，非常规超导理论的研究。迄今作为第一作者或通讯作者发表论文10余篇， 包括Physical Review Letters 3篇，Nature Communications 1篇。