Surface region enhanced superconductivity in high-Tc cuprates:
We present experimental evidence for the presence of a ab-plane surface superconducting transition Tcs which is considerably higher than the known bulk Tc in single crystal La-Ba-Cu-O. Across the range of charge carrier concentration studied in this work, the effect is pronounced when multiple correlated electronic/structural orders are simultaneously present, pointing at strong correlations as the key ingredient. Our findings indicate crystal surfaces can be the locus of nontrivial interplay of superconducting and non-superconducting orders.
