,Superconductivity of the FeSe/SrTiO3 Interface in View of BCS-BEC Crossover

• 作 者: Shuyuan Zhang Guangyao Miao Jiaqi Guan Xiaofeng Xu Bing Liu Fang Yang Weihua Wang Xuetao Zhu Jiandong Guo
• 机 构: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy o
• 出 处: 中国物理快报（英文版）
• 发表日期: 2019年10期

In paired Fermi systems,strong many-body effects exhibit in the crossover regime between the Bardeen-Cooper-Schrieffer (BCS) and the Bose-Einstein condensation (BEC) limits.The concept of the BCS-BEC crossover,which is studied intensively in the research field of cold atoms,has been extended to condensed matters.Here by analyzing the typical superconductors within the BCS-BEC phase diagram,we find that FeSe-based superconductors are prone to shift their positions in the BCS-BEC crossover regime by charge doping or substrate substitution,since their Fermi energies and the superconducting gap sizes are comparable.Especially at the interface of single-layer FeSe on SrTiO3 substrate,the superconductivity is relocated closer to the crossover unitary than other doped FeSe-based materials,indicating that the pairing interaction is effectively modulated.We further show that hole-doping can drive the interfacial system into the phase with possible pre-paired electrons,demonstrating its flexible tunability within the BCS-BEC crossover regime.