Suppressed magnetization in La$_{0.7}$Ca$_{0.3}$MnO$_3$/YBa$_2$Cu$_3$O$_{7-\delta}$ superlattices

TL;DR

This study investigates how the magnetic properties of La$_{0.7}$Ca$_{0.3}$MnO$_3$/YBa$_2$Cu$_3$O$_{7-\delta}$ superlattices are affected by interface interactions, revealing suppressed magnetization linked to charge transfer at the interface.

Contribution

It provides detailed insights into the magnetization suppression mechanism at the interface of these superlattices, combining magnetometry, neutron reflectometry, and spectroscopy.

Findings

Magnetization decreases with increasing YBa$_2$Cu$_3$O$_{7-\delta}$ layer thickness.

Magnetization suppression is due to inhomogeneous depth profile near the interface.

Charge transfer causes increased Mn 3d band occupation, leading to ferromagnetic order suppression.

Abstract

We studied the magnetic properties of La$_{0.7}$Ca$_{0.3}$MnO$_3$ / YBa$_2$Cu$_3$O$_{7-\delta}$ superlattices. Magnetometry showed that with increasing YBa$_2$Cu$_3$O$_{7-\delta}$ layer thickness the saturation magnetization per La$_{0.7}$Ca$_{0.3}$MnO$_3$ layer decreases. From polarized neutron reflectometry we determined that this magnetization reduction is due to an inhomogenous magnetization depth profile arising from the suppression of magnetization near the La$_{0.7}$Ca$_{0.3}$MnO$_3$ / YBa$_2$Cu$_3$O$_{7-\delta}$ interface. Electron energy loss spectroscopy indicates an increased 3d band occupation of the Mn atoms in the La$_{0.7}$Ca$_{0.3}$MnO$_3$ layers at the interface. Thus, the suppression of ferromagnetic order at the La$_{0.7}$Ca$_{0.3}$MnO$_3$ / YBa$_2$Cu$_3$O$_{7-\delta}$ interface is most likely due to charge transfer between the two materials.