Staff directory Gabor Csire

Gabor Csire

Postdoctoral Researcher
Theory and Simulation



  • Gap anisotropy in multiband superconductors based on multiple scattering theory

    Saunderson T.G., Annett J.F., Újfalussy B., Csire G., Gradhand M. Physical Review B; 101 (6, 064510) 2020. 10.1103/PhysRevB.101.064510. IF: 3.575

    We implement the Bogoliubov-de Gennes equation in a screened Korringa-Kohn-Rostoker method for solving, self-consistently, the superconducting state for three-dimensional crystals. This method combines the full complexity of the underlying electronic structure and Fermi surface geometry with a simple phenomenological parametrization for the superconductivity. We apply this theoretical framework to the known s-wave superconductors Nb, Pb, and MgB2. In these materials multiple distinct peaks at the gap in the density of states were observed, showing significant gap anisotropy which is in good agreement with experiment. Qualitatively, the results can be explained in terms of the k-dependent Fermi velocities on the Fermi surface sheets exploiting concepts from BCS theory. © 2020 American Physical Society.

  • Quantitative theory of triplet pairing in the unconventional superconductor LaNiGa2

    Ghosh S.K., Csire G., Whittlesea P., Annett J.F., Gradhand M., Újfalussy B., Quintanilla J. Physical Review B; 101 (10, 100506) 2020. 10.1103/PhysRevB.101.100506. IF: 3.575

    The exceptionally low-symmetry crystal structures of the time-reversal symmetry-breaking superconductors LaNiC2 and LaNiGa2 lead to an internally antisymmetric nonunitary triplet state as the only possibility compatible with experiments. We argue that this state has a distinct signature: A double-peak structure in the density of states (DOS) which resolves in the spin channel in a particular way. We construct a detailed model of LaNiGa2 capturing its electronic band structure and magnetic properties ab initio. The pairing mechanism is described via a single adjustable parameter. The latter is fixed by the critical temperature Tc allowing parameter-free predictions. We compute the electronic specific heat and find excellent agreement with experiment. The size of the ordered moment in the superconducting state is compatible with zero-field muon spin relaxation experiments and the predicted spin-resolved DOS suggests the spin splitting is within the reach of present experimental technology. © 2020 American Physical Society.