Институт теоретической физики им. Л.Д. Ландау РАН
L.D. Landau Institute for Theoretical Physics RAS
International conference Research in superconductivity and beyond
Gerasim Eliashberg memorial conference
August, 23-26, 2021 Chernogolovka, Russia

Theory of superconductivity due to Ngai's mechanism in lightly doped SrTiO3
Date/Time: 17:00 24-Aug-2021
We develop a theory of superconducting pairing in low-density Strontium titanate based upon the idea of quadratic coupling of electron density to soft transverse optical phonons [1]. This coupling leads to static attractive potential between electrons which decays
in real space exponentially with the length leff that scales inversely with soft optical gap ωT. For low electron densities n≤1018cm−3 attraction between electrons can be considered local and superconducting transition temperature Tc is calculated using old results [2]. We use independently obtained magnitude g of the quadratic coupling strength and find Tc(n) dependence in agreement with experimental data [3]
for low doping. Next, we show that suppression of Tc by hydrostatic pressure [4] and strong increase of Tc due to isotop substitution 16O→18O observed in [5] are qualitatively explained within our theory.

[1] K. L. Ngai, Phys. Rev. Lett. 32, 215 (1974)
[2] L. P. Gor'kov and T. K. Melik-Barkhudarov, Sov. Phys. JETP 40, 1452-1458 (1961)
[3] X. Lin, G. Bridoux, A. Gourgout, G. Seyfarth, S. Kramer, M. Nardone, B. Fauque, and K. Behnia, Phys. Rev. Lett. 112, 207002 (2014).
[4] C. Enderlein, J. Ferreira de Oliveira, D. A. Tompsett, E. Baggio Saitovitch, S. S. Saxena, G. G. Lonzarich and S. E. Rowley, Nature Comm. (2020), https://doi.org/10.1038/s41467-020-18438-0

[5] A. Stucky, G. W. Scheerer, Z. Ren, D. Jaccard,
J.-M. Poumirol, C. Barreteau, E. Giannini and D. van der Marel, Scientific
Reports, 6:37582 (2016) DOI: 10.1038/srep37582


Feigel'man Mikhail V. (Presenter)
(no additional information)

D E Kiseliov
(no additional information)

© 2012, Landau Institute for Theoretical Physics RAS www.itp.ac.ru
Contact webmaster