Overdoping YBa2Cu3O7 via a heterostructure with La0.67Sr0.33MnO3

TL;DR

This study demonstrates a method to overdoped YBa2Cu3O7 by creating a heterostructure with La0.67Sr0.33MnO3, revealing new insights into its electronic structure and superconducting properties.

Contribution

The paper introduces a heterostructure approach to achieve overdoping in YBCO, enabling exploration of its unconventional superconductivity under magnetic influence.

Findings

Charge transfer indicates overdoped YBCO in heterostructure

Surface and bulk electronic structures differ but converge in bilayer

Superconductivity persists despite magnetic order

Abstract

YBa2Cu3Ox, the first superconductor discovered with Tc higher than 77 K, is among the most complex cuprates having both CuO chains and plains in the structure. YBa2Cu3O7 (YBCO) exhibits slightly overdoped behavior and further doping is difficult as all the lattice sites in the CuO chains are occupied. We have grown high quality single crystalline films of YBCO and bilayer La0.67Sr0.33MnO3 (LSMO)/YBCO exhibiting superconductivity in both the cases. Photoemission spectra reveal different surface and bulk electronic structures; the difference reduces in the bilayer. Evidence of charge transfer across the bilayer interface is observed in the valence band and core level spectra indicating an overdoped condition in YBCO. While superconductivity in the presence of magnetic order in the bilayer is puzzling, this pathway to reach overdoped regime in YBCO opens up a new landscape to probe the exotic physics of unconventional superconductivity.