SKM 2023 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 63: Superconductivity: Theory
TT 63.7: Talk
Friday, March 31, 2023, 11:00–11:15, HSZ 103
Finite energy Cooper pairing in multiband superconductors — •Masoud Bahari1, Song-Bo Zhang2, Chang-An Li1, Sang-Jun Choi1, Carsten Timm3, and Björn Trauzettel1 — 1University of Würzburg, Würzburg, Germany — 2University of Zürich, Zürich, Switzerland — 3Technische Universität Dresden, Dresden, Germany
Extensive efforts have been carried out to understand the superconducting pairing symmetry since the birth of Bardeen-Cooper-Schrieffer theory. In weakly interacting systems, the essential ingredient is a weak effective electron-electron interaction at the Fermi energy resulting in particular bulk properties including superconducting gaps possibly with nodes.
We demonstrate and discuss the bulk and surface spectral properties of a novel pairing mechanism that occurs at finite excitation energies in multiband superconductors. In the bulk, it is manifested by the appearance of superconducting coherence peaks in the density of states at finite energies. Interestingly, on the surface, we predict the emergence of a pair of helical topological Dirac surface cones when the finite energy pairing is odd-parity.
Finally, we propose aluminum in proximity with (111) surface of gold to realize the bulk properties of finite energy pairing. We discuss the pairing symmetry of the system by employing the density-functional theory, and an analytical model based on the Bogoliubov-de Gennes formalism. The signature of such a pairing gives important information about the correct pairing symmetry of a superconductor.