Berlin 2005 – scientific programme
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TT: Tiefe Temperaturen
TT 18: Superconductivity - Properties, Electronic Structure, Order Parameter II
TT 18.1: Invited Talk
Monday, March 7, 2005, 10:00–10:30, TU H2053
Two-Gap Superconductivity in MgB2 — •Thomas Dahm — Universität Tübingen, Institut für Theoretische Physik
It is by now generally accepted that the recently discovered superconductor MgB2 is a superconductor with two energy gaps. In this talk we discuss how this happens and address some of its unusual implications. Measurements of the microwave conductivity on MgB2 thin films have shown an anomalous coherence peak appearing at significantly lower temperatures than in conventional superconductors [1] and the anisotropy ratio of the upper critical field in MgB2 single crystals shows an unusual strong temperature dependence. We argue that both of these observations are natural consequences of the existence of the two gaps, if the special Fermi surface structure of MgB2 is taken into account [1,2]. We also examine consequences for the expected intrinsic nonlinear microwave response in MgB2 [3].
[1] B.B.Jin, T.Dahm et al, Phys. Rev. Lett. 91, 127006 (2003).
[2] T.Dahm and N.Schopohl, Phys. Rev. Lett. 91, 017001 (2003).
[3] T.Dahm and D.J.Scalapino, Appl. Phys. Lett. 85, 4436 (2004).