Thermal and Quantum critical Properties of overdoped La_{2-x}Sr_{x}CuO_{4}

Abstract

We analyze the extended superfluid density data of Božović \textit{ et al}. taken on homogenous thin films to explore the critical properties of the thermal (TSM) and quantum superconductor to metal (QSM) transitions in overdoped La${}_{2-x}$Sr${}_x$CuO${}_4$. The temperature dependence reveals remarkable agreement with d-wave BCS behavior, where $\sigma \propto 1/{\lambda }^2$. No sign of the expected KTB transition is observable. We show that the critical amplitude ${\rho }_{s0}={\rho }_s\left(T\right)/\left(1-T/T_c\right)$ scales as $T_c\propto {\rho }_{s0}^{1/2}$ and with that as $T_c\propto {\rho }_s\left(0\right)$, empirically verified by Božović \textit{et al}. Together with additional evidence for BCS behavior in overdoped La${}_{2-x}$Sr${}_x$CuO${}_4$ we show that the scaling relation $T_c\propto \lambda {\left(0\right)}^{-1}\propto \Delta \left(0\right)\propto \xi {\left(0\right)}^{-1}\propto H_{c2}{\left(0\right)}^{-1/2}\propto {\lambda }_0^{-1}\propto {\Delta }_0\propto {\xi }_0^{-1}\propto H_{c20}^{-1/2}$ applies, by approaching the QSM and TSM transitions. This differs from the dirty limit behavior $\lambda \left(0\right)\propto \xi {\left(0\right)}^{1/2}$, maintains the $T_c$ \ independence of the Ginzburg-Landau parameter $\kappa ={\lambda }_o/{\xi }_0$, and puts a stringent constraint on the effect at work. We notice that potential candidates appear to be the nonlocal effects on the penetration depth of clean d-wave superconductors explored by Kosztin and Legget.

References in corpus (1)

• Superconductor-to-Metal Quantum Phase Transition in Overdoped $L{a}_{2-x}S{r}_{x}Cu{O}_4$