S. Brazovskii, P. Monceau and N. Kirova
J. Phys. IV France 131 (2005) 49-54
Feshbach shape resonances in nanoscale multiband systems for high Tc superconductivityM. Filippi1, A. Bianconi1 and A. Bussmann-Holder2
1 Department of Physics, University of Rome La Sapienza, Ple. A. Moro 2, 00185 Roma, Italy
2 Max-Planck-Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
We show that electron doped MgB2, made of a superlattice of boron honeycomb layers, is a multiband superconductor in the clean limit that provides the simplest high T superconducting system (HTcS) called also the atomic hydrogen for HTcS. The chemical potential has been tuned by atomic substitution keeping the superconductivity in the clean limit. This is a two component electronic system made of a first Fermi gas in the subband that coexists with a second low density electron fluid in the subband close the localization limit . The Feshbach shape resonance of the interband exchange-like pairing term centered at the 2D to 3D Lifshitz electronic topological transition ( ETT) is shown to be the key term controlling the critical temperature in the range from 0.3 K to 40 K.
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