Phonon modes and electron-phonon coupling at the FeSe/SrTiO<sub>3</sub> interface
ORAL
Abstract
The remarkable increase in superconducting transition temperature (Tc) observed at the interface of one-unit-cell FeSe films on SrTiO3 substrates (1 uc FeSe/STO) has attracted considerable research into the interface effects. Although this high Tc is thought to be associated with electron-phonon coupling (EPC), the microscopic coupling mechanism and its role in the superconductivity remain elusive. Here we uncover new optical phonon modes, coupling strongly with electrons, in the energy range of 75-99 meV. These modes are characterized by out-of-plane vibrations of oxygen atoms in the interfacial double-TiOx layer and the apical oxygen in STO. These findings shed light on the microscopic origin of the interfacial EPC and provide insights into achieving large and consistent Tc enhancement in FeSe/STO and potentially other superconducting systems.
*This work was primarily supported by the US Department of Energy (DOE), Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award No. DE-SC0014430 (H.Y. and X.P.). Further support was provided by the DOE's National Nuclear Security Administration under grant no. GRANT13583770 (F.G. and X.P.) and the National Science Foundation through the Materials Research Science and Engineering Center program under grant award no. DMR-2011967 (X.Y. and X.P.). Y.Z. and R.W. were supported by the US DOE, Office of Science (grant no. DE-FG02-05ER46237).
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Presenters
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Yinong Zhou
- Auburn University