Temperature dependence of upper critical fields and coherence lengths for optimally-doped $YB{a}_{2}C{u}_3{O}_{7-\delta }$ thin films

Abstract

We report the comprehensive comparative analysis of the upper critical magnetic fields ${\mu }_0{H}_{c2}(0)$ obtained within Ginzburg-Landau and Werthamer-Helfand-Hohenberg theories for optimally-doped $YB{a}_{2}C{u}_3{O}_{7-\delta }$ thin films. For different orientations of the magnetic field, our calculations give 638 and 153 T for ${\mu }_0{H}_{c2}(0)$, H || ab and ${\mu }_0{H}_{c2}(0)$, H || c, respectively, when using $H_{c2}(0)$. For the first time, the temperature dependences of coherence lengths ${\xi }_{ab}(T)$ and ${\xi }_c(T)$ within proposed theories were determined using 50 and 90% criteria of the normal state resistivity value ${\rho }_N$. The Ginzburg-Landau 0.9${\rho }_N$ approach gives ${\xi }_{ab}(0)$=11.8 A, and ${\xi }_c(0)$=3.0 A which are in a good agreement with literature data. The implications of very short coherence lengths in HTSCs are discussed.

Table 3, figures 5, pages 9

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• Transport and pinning properties of Ag-doped FeSe0.94
• Pseudogap transition within the superconducting phase in the three-band Hubbard model