Berlin 2024 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 18: Superconductivity: Poster
TT 18.10: Poster
Monday, March 18, 2024, 15:00–18:00, Poster C
The three Fermi pockets of NbSe2 - Investigating a Kohn-Luttinger like mechanism in TMDC monolayers. — •Julian Siegl, Anton Bleibaum, Magdalena Marganska-Lyzniak, John Schliemann, and Milena Grifoni — Institute for Theoretical Physics, University of Regensburg, Regensburg, Germany
We investigate a possible superconducting pairing generated by competing Coulomb repulsion processes in monolayer NbSe2. The two spin-orbit split Fermi surfaces (FS) of ML NbSe2 in the K and K′ valley can support a superconducting gap, with predominant f-wave symmetry, when the short-range intervalley scattering is stronger than the long-range intravalley one. Upon inclusion of the third FS centered at the Gamma point an additional competing pairing channel favoring s-wave symmetry opens for strong interpocket scattering. The competition between these two channels is governed by the relative strengths of the three processes involved, resulting either in one, two or three symmetry related values of the gaps at the FSs. We estimate the relevant interactions by calculating the dielectric susceptibility and the screened Coulomb potential in the RPA approximation for a DFT-based tight-binding model. The multi-orbital nature of the valence band results in preferential screening of short-range scattering processes, favoring the interpocket scattering. Far from being a spectator, the third Fermi pocket turns out to be a powerful player, even to the point of changing the symmetry of the order parameter.
Keywords: superconductivity; unconventional symmetry; tmdc; nbse2