title: High temperature superconducting FeSe films on SrTiO3 substrates.
abstract: Interface enhanced superconductivity at two dimensional limit has become one of most intriguing research directions in condensed matter physics. Here, we report the superconducting properties of ultra-thin FeSe films with the thickness of one unit cell (1-UC) grown on conductive and insulating SrTiO3 (STO) substrates. For the 1-UC FeSe on conductive STO substrate (Nb-STO), the magnetization versus temperature (M-T) measurement shows a drop crossover around 85 K. For the FeSe films on insulating STO substrate, systematic transport measurements were carried out and the sheet resistance of FeSe films exhibits Arrhenius TAFF behavior with a crossover from a single-vortex pinning region to a collective creep region. More intriguing, sign reversal of Hall resistance with temperature is observed, demonstrating a crossover from hole conduction to electron conduction above TC in 1-UC FeSe films.
authors.affiliation: 1] International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China [2].
authors.forename: Yi
authors.initials: Y
authors.lastname: Sun
authors.affiliation: 1] State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China [2] Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [3].
authors.forename: Wenhao
authors.initials: W
authors.lastname: Zhang
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xing
authors.affiliation: 1] State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China [2] Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Fangsen
authors.initials: F
authors.lastname: Li
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 1037 Luoyu road, Wuhan 430071, China.
authors.forename: Zhengcai
authors.initials: Z
authors.lastname: Xia
authors.affiliation: 1] State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China [2] Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [3] Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.affiliation: 1] State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China [2] Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [3] Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Xucun
authors.initials: X
authors.lastname: Ma
authors.affiliation: 1] State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Qi-Kun
authors.initials: QK
authors.lastname: Xue
authors.affiliation: 1] International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China [2] Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
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