Peng Rui, Zou Ke, Han M G, Albright Stephen D, Hong Hawoong, Lau Claudia, Xu H C, Zhu Yimei, Walker F J, Ahn C H
Department of Applied Physics, Yale University, New Haven, CT 06520, USA.
Center for Research on Interface Structures and Phenomena, Yale University, New Haven, CT 06520, USA.
Sci Adv. 2020 Apr 8;6(15):eaay4517. doi: 10.1126/sciadv.aay4517. eCollection 2020 Apr.
Remarkable enhancement of the superconducting transition temperature ( ) has been observed for monolayer (ML) FeSe films grown on SrTiO substrates. The atomic-scale structure of the FeSe/SrTiO interface is an important determinant of both the magnetic and interfacial electron-phonon interactions and is a key ingredient to understanding its high- superconductivity. We resolve the atomic-scale structure of the FeSe/SrTiO interface through a complementary analysis of scanning transmission electron microscopy and in situ surface x-ray diffraction. We find that the interface is more strongly bonded for a particular registration, which leads to a coherently strained ML. We also determine structural parameters, such as the distance between ML FeSe and the oxide, Se─Fe─Se bond angles, layer-resolved distances between Fe─Se, and registry of the FeSe lattice relative to the oxide. This picoscale structure determination provides an explicit structural framework and constraint for theoretical approaches addressing the high- mechanism in FeSe/SrTiO.
在生长于SrTiO衬底上的单层（ML）FeSe薄膜中，已观察到超导转变温度（ ）显著提高。FeSe/SrTiO界面的原子尺度结构是磁相互作用和界面电子-声子相互作用的重要决定因素，也是理解其高温超导性的关键因素。我们通过扫描透射电子显微镜和原位表面X射线衍射的互补分析来解析FeSe/SrTiO界面的原子尺度结构。我们发现，对于特定的配准，界面结合更强，这导致了相干应变的单层。我们还确定了结构参数，如单层FeSe与氧化物之间的距离、Se─Fe─Se键角、Fe─Se之间的层分辨距离以及FeSe晶格相对于氧化物的配准。这种皮米尺度的结构确定为解决FeSe/SrTiO中高温超导机制的理论方法提供了明确的结构框架和约束。
