Regensburg 2025 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 36: Focus Session: Ising Superconductivity in Monolayer Transition Metal Dichalcogenides (joint session TT/HL/MA)
MA 36.3: Topical Talk
Donnerstag, 20. März 2025, 10:30–11:00, H36
Friedel Oscillations and Chiral Superconductivity in Monolayer NbSe2 — •Magdalena Marganska1,2, Julian Siegl1, Anton Bleibaum1, Marcin Kurpas3, Wen Wan4, John Schliemann1, Miguel M. Ugeda4,5, and Milena Grifoni1 — 1Institute for Theoretical Physics, University of Regensburg, 93 053 Regensburg — 2Institute for Theoretical Physics, Wrocław University of Science and Technology, Wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland — 3Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland — 4Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain — 5Ikerbasque, Basque Foundation for Science, Bilbao 48013, Spain
In 1965 Kohn and Luttinger proposed a mechanism for superconductivity, based on the electronic Coulomb interaction alone. The screening effects, which cause Friedel oscillations of charge density around impurities, modulate also the interaction between moving electrons. If it has attractive regions, superconductivity can arise by exploiting them. This mechanism, negligible in 3D metals, can become much stronger in 2D electronic systems. In a monolayer of NbSe2 the screening is further suppressed, due to the multi-orbital nature of the electronic band at the Fermi level. We show how this, and the presence of K/K’ Fermi surfaces, leads to superconducting pairing. The dominant gap solution at T=0 has the chiral p+ip symmetry. It evolves with increasing temperature, turning from fully chiral at T=0 to a nematic solution with p-like symmetry close to the critical temperature. Our results are also consistent with our tunneling spectroscopy measurements in NbSe2.
Keywords: Kohn-Luttinger pairing; multiorbital superconductivity; dielectric screening; chiral superconductivity; 2D superconductivity