European Synchrotron Radiation Facility, 71 Avenue des Martyrs, F-38000 Grenoble, France.
LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Université, 75005 Paris, France.
Phys Rev Lett. 2018 Nov 9;121(19):197001. doi: 10.1103/PhysRevLett.121.197001.
We compute the compressibility of the conduction electrons in both bulk orthorhombic FeSe and monolayer FeSe on a SrTiO_{3} substrate, including dynamical electronic correlations within slave-spin mean-field + density-functional theory. Results show a zone of enhancement of the electronic compressibility crossing the interaction-doping phase diagram of these compounds in accord with previous simulations on iron pnictides and in general with the phenomenology of Hund's metals. Interestingly, at ambient pressure FeSe is found slightly away from the zone with enhanced compressibility but moved right into it with hydrostatic pressure, while in monolayer FeSe the stronger enhancement region is realized on the electron-doped side. These findings correlate positively with the enhancement of superconductivity seen in experiments, and support the possibility that Hund's induced many-body correlations boost superconductive pairing when the system is at the frontier of the normal- to Hund's metal crossover.
我们计算了体心四方相 FeSe 和单层 FeSe 在 SrTiO3 衬底上的传导电子的压缩性，包括在奴夫林-金兹堡-朗道（Slave-spin mean-field + density-functional theory）理论框架内的动力学电子相关。结果表明，在这些化合物的相互作用掺杂相图中，电子压缩性的增强区域与之前在铁磷族元素和一般的 Hund 金属现象学的模拟结果相符合。有趣的是，在环境压力下，FeSe 略微偏离了具有增强压缩性的区域，但在静水压力下会被推向这个区域，而在单层 FeSe 中，更强的增强区域出现在电子掺杂侧。这些发现与实验中观察到的超导性增强存在正相关，并且支持了 Hund 诱导的多体相关性在系统处于正常到 Hund 金属交叉前沿时增强超导配对的可能性。
