Two Superconducting Transitions in Single Crystal La$_{2-x}$Ba$_x$CuO$_4$

TL;DR

This study reveals a new surface-related superconducting transition in La$_{2-x}$Ba$_x$CuO$_4$ crystals, with a higher transition temperature than the bulk, especially near stripe-ordered doping levels.

Contribution

It uncovers a distinct surface superconducting transition in La$_{2-x}$Ba$_x$CuO$_4$, highlighting the role of surface effects and stripe correlations in high-temperature superconductivity.

Findings

Surface transition temperature $T_{cs}$ exceeds bulk $T_c$

$T_{cs}$ reaches 36 K, 1.64 times $T_c$

Surface superconductivity is prominent near stripe-ordered doping levels

Abstract

We use spatially-resolved transport techniques to investigate the superconducting properties of single crystals La$_{2-x}$Ba$_x$CuO$_4$. We find a new superconducting transition temperature $T_{cs}$ associated with the ab-plane surface region which is considerably higher than the bulk $T_c$. The effect is pronounced in the region of charge carrier doping $x$ with strong spin-charge stripe correlations, reaching $T_{cs}=36$ K or 1.64$T_c$.