Dmitry E. Kiselov: »Theory of superconductivity due to Ngai’s mechanism in lightly doped SrTiO3«

Date: Tuesday, December 5, 2023 at 11:15

Location: Seminar room for physics, JSI main building

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 $l_{eff}$ that scales inversely with soft optical gap $\omega_T$ . For low electron densities $n \leq 10^{18} cm^{-3}$ attraction between electrons can be considered local and superconducting transition temperature $T_c$ is calculated using old results [2]. We use independently obtained magnitude g of the quadratic coupling strength and find $T_c(n)$ dependence in agreement with experimental data [3] for low doping. Next, we show that suppression of $T_c$ by hydrostatic pressure [4] and strong increase of $T_c$ due to isotop substitution $^{16}O \to\,^{18}O$ 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 (1961)

[3] X. Lin, et al, Phys. Rev. Lett. 112, 207002 (2014).

[4] C. Enderlein, et al, Nature Comm. (2020)

[5] A. Stucky, et al, Scientific Reports, 6:37582 (2016




Pavel Ostrovsky»Josephson effect in strongly disordered metallic wires«

Date: Friday, November 17, 2023 at 14:00

Location: Kuščerjev seminar, Jadranska 19


The talk will also be broadcast over Zoom via the following link: https://uni-lj-si.zoom.us/j/4933857795?pwd=TnkycEJsYnRuemdjR0l6czVnTHRLUT09


Anton Potočnik : »The path towards superconducting quantum computers: interfacing qubits with classical electronics at 10 mK«

Date: Monday, October 16, 2023 at 16:15

Location: F1, Jadranska 19



Vladimir Kravtsov : »A renormalization group analysis of the Anderson localization problem in large and infinite dimensions«

Date: Thursday, October 19, 2023 at 15:00

Location: Kuščerjev seminar, Jadranska 19, 4th floor



Igor Poboiko»Theory of free fermions under random projective measurements«

Date: Thursday, October 12, 2023 at 15:00

Location: Kuščerjev seminar, Jadranska 19, 4th floor