Charging effects on the critical temperature of the Josephson-coupled layered superconductors

Abstract

Effects of quantum phase fluctuations on the critical temperature T c of Josephson-coupled layered superconductors are considered. T c is shown to decrease nonlinearly with increasing charge fluctuations. The results obtained for the critical temperature by applying the self-consistent mean field method reveal no phase transition from superconducting state to normal metal for a finite value of charging energy. The destruction of the long range phase coherence appeared to occur at asymptotically large values of self-capacitance charging. For the weak quantum phase fluctuations limit, T c is obtained to be vary in the interval of T c *< T c< T c (2), where T c (2) is the critical temperature for a single superconducting layer evaluated by the mean field theory, and T c * is the temperature when the phase coherence between the nearest neighboring layers is lost. Since T c approaches T c * with vanishing interlayer tunneling integral J ⊥. Calculation of the dependence of the transverse stiffness on the charging energy is carried out at T=0. The reentrance found can in principle occur at a sufficiently large value of the interlayer tunneling integral J ⊥> J ⊥ cr= k T c (2), where J ⊥ cr≈ k T c (2) is the value of J ⊥ when the superconductor normal metal phase transition takes place. However, the condition J ⊥≥ k T c (2) contradicts to the existence of the Josephson coupling between superconducting layers.