Atomic and electronic structures of single-layer FeSe on SrTiO 3 (001): The role of oxygen deficiency

作者：Junhyeok Bang, Zhi Li, Yi‐Yang Sun, Amit Kumar Samanta, Yuyang Zhang, Wenhao Zhang, Lili Wang, Xingzhu Chen, Xu-Cun Ma, Qi‐Kun Xue, S. B. Zhang · 发表于：Physical Review B · 年份：2013 · DOI：10.1103/physrevb.87.220503 · 被引用次数：96 · 研究领域：Iron-based superconductors research、Corporate Taxation and Avoidance、Surface and Thin Film Phenomena

Using first-principles calculation, we propose an interface structure for single triple-layer FeSe on the SrTiO${}_{3}$(001) surface, a high-${T}_{\mathrm{c}}$ superconductor found recently. The key component of this structure is the oxygen deficiency on the top layer of the SrTiO${}_{3}$ substrate, as a result of Se etching used in preparing the high-${T}_{\mathrm{c}}$ samples. The O vacancies strongly bind the FeSe triple layer to the substrate giving rise to a (2\ifmmode\times\else\texttimes\fi{}1) reconstruction, as observed by scanning tunneling microscopy. The enhanced binding correlates to the significant increase of ${T}_{\mathrm{c}}$ observed in experiment. The O vacancies also serve as the source of electron doping, which modifies the Fermi surface of the first FeSe layer by filling the hole pocket near the center of the surface Brillouin zone, as suggested from angle-resolved photoemission spectroscopy measurement.