title: Interface ferroelectric transition near the gap-opening temperature in a single-unit-cell FeSe film grown on Nb-Doped SrTiO3 substrate.
abstract: We report findings of strong anomalies in both mutual inductance and inelastic Raman spectroscopy measurements of single-unit-cell FeSe film grown on Nb-doped SrTiO3, which occur near the temperature where the superconductinglike energy gap opens. Analysis suggests that the anomaly is associated with a broadened ferroelectric transition in a thin layer near the FeSe/SrTiO3 interface. The coincidence of the ferroelectric transition and gap-opening temperatures adds credence to the central role played by the film-substrate interaction on the strong Cooper pairing in this system. We discuss scenarios that could explain such a coincidence.
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: Y-T
authors: YT
authors: Cui
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: R G
authors: RG
authors: Moore
authors: Department of Physics, Renmin University of China, Beijing 100872, China.
authors: A-M
authors: AM
authors: Zhang
authors: Department of Physics, Renmin University of China, Beijing 100872, China.
authors: Y
authors: Y
authors: Tian
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: J J
authors: JJ
authors: Lee
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: F T
authors: FT
authors: Schmitt
authors: State Key Lab of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
authors: W-H
authors: WH
authors: Zhang
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: W
authors: W
authors: Li
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: M
authors: M
authors: Yi
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: Z-K
authors: ZK
authors: Liu
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: M
authors: M
authors: Hashimoto
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors: Y
authors: Y
authors: Zhang
authors: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: D-H
authors: DH
authors: Lu
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: T P
authors: TP
authors: Devereaux
authors: State Key Lab of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China and Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors: L-L
authors: LL
authors: Wang
authors: State Key Lab of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China and Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors: X-C
authors: XC
authors: Ma
authors: Department of Physics, Renmin University of China, Beijing 100872, China.
authors: Q-M
authors: QM
authors: Zhang
authors: State Key Lab of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China and Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors: Q-K
authors: QK
authors: Xue
authors: Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA and Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors: D-H
authors: DH
authors: Lee
authors: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: Z-X
authors: ZX
authors: Shen