Stoichiometric Growth of Monolayer FeSe Superconducting Films Using a Selenium Cracking Source
Kejing Zhu,
Heng Wang,
Yuying Zhu,
Yunyi Zang,
Yang Feng,
Bingbing Tong,
Dapeng Zhao,
Xiangnan Xie,
Kai Chang,
Ke He,
Chong Liu
Affiliations
Kejing Zhu
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Heng Wang
State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
Yuying Zhu
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Yunyi Zang
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Yang Feng
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Bingbing Tong
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Dapeng Zhao
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Xiangnan Xie
State Key Laboratory of High Performance Computing, College of Computer Science and Technology, National University of Defense Technology, Changsha 410073, China
Kai Chang
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Ke He
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Chong Liu
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
As a novel interfacial high-temperature superconductor, monolayer FeSe on SrTiO3 has been intensely studied in the past decade. The high selenium flux involved in the traditional growth method complicates the film’s composition and entails more sample processing to realize the superconductivity. Here we use a Se cracking source for the molecular beam epitaxy growth of FeSe films to boost the reactivity of the Se flux. Reflection high-energy electron diffraction shows that the growth rate of FeSe increases with the increasing Se flux when the Fe flux is fixed, indicating that the Se over-flux induces Fe vacancies. Through careful tuning, we find that the proper Se/Fe flux ratio with Se cracked that is required for growing stoichiometric FeSe is close to 1, much lower than that with the uncracked Se flux. Furthermore, the FeSe film produced by the optimized conditions shows high-temperature superconductivity in the transport measurements without any post-growth treatment. Our work reinforces the importance of stoichiometry for superconductivity and establishes a simpler and more efficient approach to fabricating monolayer FeSe superconducting films.
