Regensburg 2002 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 10: Supraleitung: Theorie
TT 10.2: Vortrag
Dienstag, 12. März 2002, 10:30–10:45, H18
Electronic theory for superconductivity in Sr2RuO4: triplet pairing due to spin-fluctuation exchange — •Ilya Eremin, Dirk Manske, Christian Joas, and Karl Bennemann — Institut fuer Theoretische Physik, Freie Universitaet Berlin, D-14195 Berlin
Using the Hubbard Hamiltonian for the three electronic bands crossing the Fermi level in Sr2RuO4 we calculate the dynamical spin susceptibility χ(q, ω) in quantitative agreement with nuclear magnetic resonance (NMR) and inelastic neutron scattering (INS) experiments. The calculated susceptbility has two peaks at Qi = (2π/3, 2π/3) due to nesting properties of the Fermi surface belonging to the α- and β-bands and at qi = (0.2π, 0) due to the tendency towards ferromagnetism of the γ-band. Nesting is stronger for out-of-plane χ⊥(q,ω). Applying spin-fluctuation exchange theory for Cooper-pairing as in layered cuprates we determine from the Fermi surface topology and the elementary excitations that superconductivity in Sr2RuO4 consists of triplet pairing. Thus we can exclude s− and d−wave symmetry for the superconducting order parameter. We find a superconducting gap with nodes between RuO2 planes.