Ryee Siheon, Witt Niklas, Wehling Tim O
I. Institute of Theoretical Physics, <a href="https://ror.org/00g30e956">University of Hamburg</a>, Notkestrasse 9, 22607 Hamburg, Germany.
<a href="https://ror.org/0149pv473">The Hamburg Centre for Ultrafast Imaging</a>, Luruper Chaussee 149, 22761 Hamburg, Germany.
Phys Rev Lett. 2024 Aug 30;133(9):096002. doi: 10.1103/PhysRevLett.133.096002.
The recent discovery of superconductivity in La_{3}Ni_{2}O_{7} with T_{c}≃80 K under high pressure opens up a new route to high-T_{c} superconductivity. This material realizes a bilayer square lattice model featuring a strong interlayer hybridization unlike many unconventional superconductors. A key question in this regard concerns how electronic correlations driven by the interlayer hybridization affect the low-energy electronic structure and the concomitant superconductivity. Here, we demonstrate using a cluster dynamical mean-field theory that the interlayer electronic correlations (IECs) induce a Lifshitz transition resulting in a change of Fermi surface topology. By solving an appropriate gap equation, we further show that the leading pairing instability, s± wave, is enhanced by the IECs. The underlying mechanism is the quenching of a strong ferromagnetic channel, resulting from the Lifshitz transition driven by the IECs. Based on this picture, we provide a possible reason of why superconductivity emerges only under high pressure.
最近在高压下发现的La₃Ni₂O₇超导电性，其临界温度Tc≃80 K，为高温超导开辟了一条新途径。这种材料实现了一种双层正方形晶格模型，与许多非常规超导体不同，它具有很强的层间杂化。在这方面，一个关键问题是由层间杂化驱动的电子关联如何影响低能电子结构和伴随的超导电性。在这里，我们使用团簇动力学平均场理论证明，层间电子关联（IECs）会引发里夫希茨转变，导致费米面拓扑结构发生变化。通过求解适当的能隙方程，我们进一步表明，IECs增强了主导配对不稳定性，即s±波。其潜在机制是由IECs驱动的里夫希茨转变导致强铁磁通道的淬灭。基于这一情况，我们给出了为什么超导电性仅在高压下出现的一个可能原因。
