Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 99: Superconductivity: (General) Theory 2
TT 99.9: Vortrag
Donnerstag, 19. März 2015, 17:15–17:30, H 2053
Collective modes in superconducting rhombohedral graphite — •Ville Kauppila1, Timo Hyart2, and Tero Heikkilä2 — 1O.V. Lounasmaa Laboratory, Aalto University, Finland — 2University of Jyväskylä, Finland
Recently it was realized that coupling particles with a Dirac dispersion (such as electrons in graphene) can lead to a topologically protected state with flat band dispersion. Such a state could support superconductivity with unusually high critical temperatures[1]. Perhaps the most promising way to realize such coupling in real materials is in the surface of rhombohedrally stacked graphite.
We consider collective excitations (i.e. the Higgs modes) in surface superconducting rhombohedral graphite. We find two amplitude and two phase modes corresponding to the two surfaces of the graphite where the superconductivity lives. We calculate the dispersion of these modes. We also derive the Ginzburg-Landau theory for this material. We show that in superconducting rhombohedral graphite, the collective modes, unlike in conventional BCS superconductors, give a large contribution to thermodynamic properties of the material.
[1] T.T. Heikkila, N.B. Kopnin, G.E. Volovik,
Phys. Rev. B 83, 220503(R) (2011)