A superconductor made by a metal heterostructure at the atomic limit tuned at the `shape resonance': MgB2*

A Bianconi, D Di Castro, S Agrestini, G Campi, N L Saini, A Saccone, S De Negri, M Giovannini
2001 Journal of Physics: Condensed Matter  
We have studied the variation of Tc with charge density and lattice parameters in Mg1-xAlxB2 superconducting samples at low Al doping x<8%. We show that high Tc occurs where the chemical potential is tuned at a "superconducting shape resonance" near the energy Ec of the quantum critical point (QCP) for the dimensional transition from 2D to 3D electronic structure in a particular subband of the natural superlattice of metallic atomic boron layers. At the "shape resonance" the electrons pairs see
more » ... electrons pairs see a 2D Fermi surface at EF-w0 and a 3D Fermi surface at EF+wo, where wo is the energy cut off of the pairing interaction. The resonant amplification occurs in a narrow energy range where EF-Ec is in the range of 2wo.
doi:10.1088/0953-8984/13/33/318 fatcat:uf775bx3mzduxcpijzm6tu542e