2021/05/09 by T. Schneider, Schneider, T.
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #FOS: Physical sciences #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.2105.03975
openalex publication_date 2021/05/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The superfluid density of overdoped La2-xSrxCuO4 thin films of high quality have been measured with Tc (defined by the onset of the Meissner effect) from 5.1 to 41.6 K by Bosovic et al. Given this Tc the superfluid density shows no clear evidence of critical fluctuations and no indication of vortex unbinding as T->Tc. Nevertheless, the superfluid density displays the expected behavior for for a quantum phase transition (QPT) in the (3+1)D-xy universality class, rho(T=0)~Tc2. However, this relation is also a hallmark of dirty superconductors, treated in the mean-field approximation. Here we attempt to clear out the nature of the suppression of ro(T) as Tc->0. Noting that for any finite system the continuous transition will be rounded we perform a finite size scaling analysis. It uncovers that the ro(T) data data are consistent with a finite length limited 3D-xy transition. In some films it is their thickness and in others their inhomogeneity that determines the limiting length. Having established the precondition for the occurrence of a QPT mapping on the (3+1) D-xy model, we explore the consistency with the hallmarks of this transition. In particular with the relations rho(T)/rho(0)=1-ycT/Tc, rho((0)Tc2, yc=alpha*Tc/ro(0), where alpha is the coefficient in rho(T)=rho(0)-alphaT as T->0. The emerging agreement with these characteristics points clearly to a quantum fluctuations induced suppression, revealing the crossover from the thermal to the quantum critical regime as Tc ->0. In the classical-quantum mapping it corresponds to a 3D to (3 + 1)D crossover.