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TT: Fachverband Tiefe Temperaturen

TT 106: Complex Oxides: Bulk Properties, Surfaces and Interfaces (joint session TT/MA/KFM)

TT 106.1: Talk

Friday, March 16, 2018, 09:30–09:45, H 0110

Superconductivity in strontium titanate within the dielectric function method — •Serghei Klimin¹, Jacques Tempere¹, Jozef Devreese¹, Cesare Franchini², and Georg Kresse² — ¹TQC, Universiteit Antwerpen, Antwerpen, Belgium — ²University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna, Austria

Strontium titanate exhibits unique features which are not encountered in conventional polar crystals at the same conditions. It becomes a superconductor at unusually low carrier densities. SrTiO₃ is probably the only substance where superconductivity and optical absorption can be convincingly attributed to the Fröhlich-like electron-phonon interaction and polarons. In the present talk, we report on our theoretical studies of superconductivity in strontium titanate with a comparative discussion of different theoretical interpretations of superconductivity in SrTiO₃. It is demonstrated that the dielectric function method used in our works [1] adequately describes the superconducting phase transition using only parameters available from experiments and microscopic calculatuions. We are particularly focused on unusual isotope effect in SrTiO₃. It is shown that renormalization of optical-phonon frequencies following from the isotope substitution leads to an increase of the critical temperature within the dielectric function method.
S. N. Klimin, J. Tempere, J. T. Devreese, and D. van der Marel, Phys. Rev. B 89, 184514 (2014); J. Sup. Nov. Magn. 30, 757 (2017).