Abstract
Charge transfer and electron-phonon coupling (EPC) are proposed to be two important constituents associated with enhanced superconductivity in the single unit cell FeSe films on oxide surfaces. Using high-resolution electron energy loss spectroscopy combined with first-principles calculations, we have explored the lattice dynamics of ultrathin FeSe films grown on SrTiO3. We show that, despite the significant effect from the substrate on the electronic structure and superconductivity of the system, the FeSe phonons in the films are unaffected. The energy dispersion and linewidth associated with the Fe- and Se-derived vibrational modes are thickness and temperature independent. Theoretical calculations indicate the crucial role of antiferromagnetic correlation in FeSe to reproduce the experimental phonon dispersion. Importantly, the only detectable change due to the growth of FeSe films is the broadening of the Fuchs-Kliewer (F-K) phonons associated with the lattice vibrations of SrTiO3(001) substrate. If EPC plays any role in the enhancement of film superconductivity, it must be the interfacial coupling between the electrons in FeSe film and the F-K phonons from substrate rather than the phonons of FeSe.
| Original language | English |
|---|---|
| Article number | 035408 |
| Journal | Physical Review B |
| Volume | 97 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 8 2018 |
Funding
X.Z. and J.G. thank Dr. Fang Zhou for providing the single crystalline FeSe bulk samples to do the initial test. The work was supported by the National Natural Science Foundation of China (Grant No. 11634016), the National Key R&D Program of China (Grant No. 2017YFA0303600). X.Z. was partially supported by the Youth Innovation Promotion Association of Chinese Academy of Sciences (CAS), and the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics. Y.W. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division. Part of this work (T.B.) was conducted at the Center for Nanophase Materials Sciences, sponsored by the Scientific User Facilities Division (SUFD), Basic Energy Sciences (BES), DOE, under contract with UT-Battelle. CPU time was provided in part by resources supported by the University of Tennessee and Oak Ridge National Laboratory Joint Institute for Computational Sciences. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. DOE under Contract No. DE-AC02-05CH11231. J.Z. was partially supported by U.S. NSF through Grant No. DMR 1608865, and the sabbatical program of the Institute of Physics CAS. The work was supported by the National Natural Science Foundation of China (Grant No. 11634016), the National Key R&D Program of China (Grant No. 2017YFA0303600). X.Z. was partially supported by the Youth Innovation Promotion Association of Chinese Academy of Sciences (CAS), and the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics. Y.W. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division. Part of this work (T.B.) was conducted at the Center for Nanophase Materials Sciences, sponsored by the Scientific User Facilities Division (SUFD), Basic Energy Sciences (BES), DOE, under contract with UT-Battelle. CPU time was provided in part by resources supported by the University of Tennessee and Oak Ridge National Laboratory Joint Institute for Computational Sciences. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. DOE under Contract No. DE-AC02-05CH11231. J.Z. was partially supported by U.S. NSF through Grant No. DMR 1608865, and the sabbatical program of the Institute of Physics CAS.
| Funders | Funder number |
|---|---|
| Oak Ridge National Laboratory Joint Institute for Computational Sciences | |
| Scientific User Facilities Division | |
| U.S. NSF | DMR 1608865 |
| U.S. Department of Energy | |
| Office of Science | DE-AC02-05CH11231 |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | |
| University of Tennessee | |
| Division of Materials Sciences and Engineering | |
| Institute of Physics | |
| National Natural Science Foundation of China | 11634016 |
| Chinese Academy of Sciences | |
| Norsk Sykepleierforbund | |
| Youth Innovation Promotion Association of the Chinese Academy of Sciences | |
| State Key Laboratory of Low-Dimensional Quantum Physics | |
| National Key Research and Development Program of China | 2017YFA0303600 |