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Microwave Conductivity in Two-Band Superconductors V3+x Si1−x
We present the results of investigations of the temperature dependences of complex conductivity σ(T) = σ′(T)−iσ″(T) at frequency 9.4 GHz in series of single crystals V3+xSi1−x with different Si content. The data exhibit peculiarities typical for multiband superconductors, namely a nonlinear temperature dependence of resistivity above superconducting transition temperature Tc, suppression of superconducting transition temperature Tc by nonmagnetic impurities, a positive curvature of σ″(T) curves close to Tc, and a coherence peak in σ′(T) at T∼Tc/2. Using a two-band model in the weak-coupling regime, we demonstrate that the behavior of Tc and the evolution of σ(T) with Si-content variation are consistently described by changing of the interband scattering rate.