Superconductivity above 28 K in single unit cell FeSe films interfaced with GaO2-δ layer on NdGaO3(1 1 0)

• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2019,（8）
• 页码范围: 490-494
• 页数: 5页
• 语种: 英文

摘要

The discovery of high temperature superconductivity in single unit cell (UC) FeSe on TiO2-δ terminated perovskite SrTiO3(0 0 1) substrates [1] has attracted intensive attention on searching for new superconducting systems with engineered interfaces as well as understanding the mechanism of interface high temperature superconductivity. In stark contrast to bulk FeSe-a superconductor with transition temperature Tc～8 K at ambient pressure [2], the single UC FeSe on SrTiO3(0 0 1) becomes superconducting at Tc～65 K [3–5] or higher [6,7], holding the record Tc among all known Fe-based superconductors. The superconducting gap is enhanced by one order of magnitude compared to the value of bulk FeSe, i.e. 20 meV [1] vs. 2.2 meV [8]. What is more interesting is that monolayer FeSe on several TiO2-δ terminated substrates, such as BaTiO3 [9], SrTiO3(1 1 0) [10–12] and TiO2 [13,14], exhibit similarly high transition temperatures, despite the variation of lattice constant [15,16]. The common features shared by all these 1-UC FeSe/TiO2-δ systems are the enlarged electron pockets at the Brillouin zone (BZ) corners [3,17,18] and emergent replica bands 90–100 meV from the main bands [11,14,18].