Fluctuation contribution to the specific heat in non-Fermi models for superconductivity

Abstract

We investigate the fluctuation contribution to the specific heat of a two-dimensional superconductor with a non-Fermi normal state described by a Anderson Green's function $G(k,i\omega )={\omega }_c^{-\alpha }/(i\omega -{\epsilon }_k{)}^{1-\alpha }$. The specific heat corrections contain a term proportional to $(T^{2\alpha -T_c^{2\alpha }}{)}^{-1}$ and another logarithmic one. We defined a coherence length as function of the non-Fermi parameter $\alpha$, which showed that a crossover study between BCS and Bose-Einstein condensation is possible by varying $\alpha$ in an interval $0÷{\alpha }_{cr}$. By comparing our theoretical results with the experimental data for HTSC materials, we reobtained the value for $\alpha$, corresponding to such systems, of the order $0.3÷0.45$. We also reobtained the critical temperature for such a superconductor using the Thouless criterion.

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