Within the two-band model of superconductivity, we study the dependence of the critical temperature T, and of the isotope exponent a in the proximity to an electronic topological transition (ETT). The ETT is associated with a 3D-2D crossover of the Fermi surface of one of the two bands: the sigma subband of the diborides. Our results agree with the observed dependence of T(c) on Mg content in A(1-a)Mg(a)B(2) (A = Al or Sc). where an enhancement of T, can be interpreted as due to the proximity to a 'shape resonance.' Moreover we have calculated a possible variation of the isotope effect oil the superconducting critical temperature by tuning the chemical potential.
Multiband superconductors close to a 2D-3D electronic topological transition
ANGILELLA, Giuseppe Gioacchino Neil;
2005-01-01
Abstract
Within the two-band model of superconductivity, we study the dependence of the critical temperature T, and of the isotope exponent a in the proximity to an electronic topological transition (ETT). The ETT is associated with a 3D-2D crossover of the Fermi surface of one of the two bands: the sigma subband of the diborides. Our results agree with the observed dependence of T(c) on Mg content in A(1-a)Mg(a)B(2) (A = Al or Sc). where an enhancement of T, can be interpreted as due to the proximity to a 'shape resonance.' Moreover we have calculated a possible variation of the isotope effect oil the superconducting critical temperature by tuning the chemical potential.| File | Dimensione | Formato | |
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