Superconducting properties of under- and over-doped BaxK1−xBiO₃ perovskite oxide

Abstract

In this study, we investigate the thermodynamic properties of the Ba[Formula: see text]K[Formula: see text]BiO3 (BKBO) superconductor in the under- (x = 0.5) and over-doped (x = 0.7) regime, within the framework of the Migdal–Eliashberg formalism. The analysis is conducted to verify that the electron–phonon pairing mechanism is responsible for the induction of the superconducting phase in the mentioned compound. In particular, we show that BKBO is characterized by the relatively high critical value of the Coulomb pseudopotential, which changes with doping level and does not follow the Morel–Anderson model. In what follows, the corresponding superconducting band gap size and related dimensionless ratio are estimated to increase with the doping, in agreement with the experimental predictions. Moreover, the effective mass of electrons is found to take on high values in the entire doping and temperature region. Finally, the characteristic dimensionless ratios for the superconducting band gap, the critical magnetic field and the specific heat for the superconducting state are predicted to exceed the limits set within the Bardeen–Cooper–Schrieffer theory, suggesting pivotal role of the strong-coupling and retardation effects in the analyzed compound. Presented results supplement our previous investigations and account for the strong-coupling phonon-mediated character of the superconducting phase in BKBO at any doping level.

Revealing the anisotropy effects on the critical magnetic field in CaC6 superconductor

“…where λ αβ denotes the electron-phonon coupling con- stant, which is defined in the matrix form as follows [24]: (4) The Eliashberg equations (1) and (2) are numerically solved by using the modified numerical procedures initially developed for the isotropic materials [25][26][27][28][29] and later adopted to three-band CaC 6 superconductor [12]. In this context, the input parameters for the calculations are the critical temperature T C = 11.5 K and the corresponding elements of the Coulomb pseudopotential (µ ⋆ αβ ) matrix [24]: 4) and (5) are arranged with respect to the assumed band indices.…”

Characteristics of the s–Wave Symmetry Superconducting State in the BaGe3 Compound

“…The Eliashberg equations were solved numerically. We made use of the finite difference approximation of Newton's method and assumed M = 1100, like in our other studies [37][38][39][40]. We obtained the stability of solutions of the Eliashberg equations within the temperature range from T 0 = 0.6 K to T c .…”

ABO3 and A1−xCxB1−yDy(O1−zEz)3: review of experimental optimisation of thin film perovskites by high-throughput evaporative physical vapour deposition

“…Perovskites can also be used as catalysts in fuel cells for oxygen reduction and oxygen evolution reactions. [4][5][6][7][8] Indeed, perovskites materials find applications in photovoltaics [9][10][11][12][13] , superconductors [14][15][16][17] , giant magneto-resistors [18][19][20] , LEDs [21][22][23][24][25] and lasers. 26,27 We describe here how combinatorial synthesis by ePVD provides the first step in a flexible and powerful high throughput methodology in optimising the function of perovskites.…”