Superconductivity depression in ultrathin YBa2Cu3O7-x layers in La0.7Ca0.3MnO3 /YBa2Cu3O7-x superlattices

TL;DR

This study investigates how ultrathin YBa2Cu3O7-x layers in superlattices with La0.7Ca0.3MnO3 suppress superconductivity as their thickness decreases, highlighting interface effects and magnetic interactions.

Contribution

It demonstrates the critical thickness below which superconductivity is suppressed in YBCO layers within LCMO/YBCO superlattices, with detailed structural analysis confirming sharp interfaces.

Findings

Superconductivity persists down to 3 unit cells of YBCO.

Superconducting critical temperature drops from 85 K at 12 unit cells to zero below 3.

Sharp interfaces with minimal disorder were observed in the superlattices.

Abstract

We report on the depression of the superconducting critical temperature of ultra thin YBa2Cu3O7 (YBCO) layers, when their thickness is reduced in presence of La0.7Ca0.3MnO3 (LCMO) magnetic layers in [LCMO (15 u.c.)/ YBCO(N u.c.)] superlattices. The thickness of the manganite layer is kept at 15 unit cells and the YBCO thickness is varied between N=12 and N=1 unit cells. The structural analysis using x-ray diffraction and electron microscopy shows sharp interfaces with little structural disorder. While a critical temperature, Tc=85 K is found for 12 YBCO unit cells, superconductivity is completely suppressed for YBCO layer thickness below 3 unit cells. The possible interaction between superconductivity and magnetism is investigated.