Effect of Interface Induced Exchange Fields on Cuprate-Manganite Spin Switches

TL;DR

This study investigates how interface-induced exchange fields influence the inverse spin switch behavior in LCMO/YBCO/LCMO trilayers, revealing that magnetoresistance depends on the interplay between applied fields and induced exchange fields rather than just magnetization orientation.

Contribution

It demonstrates that the magnetoresistance in these trilayers is governed by the interplay of external magnetic fields and interface-induced exchange fields, challenging previous theoretical assumptions.

Findings

Magnetization profiles and magnetoresistance depend on the interplay of applied field and exchange field.

Relative orientation of LCMO magnetizations does not solely determine magnetoresistance.

Induced exchange fields originate from electronic reconstruction at interfaces.

Abstract

We examine the anomalous inverse spin switch behavior in La$_{0.7}$Ca$_{0.3}$MnO$_3$ (LCMO)/YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO)/LCMO trilayers by combined transport studies and polarized neutron reflectometry. Measuring magnetization profiles and magnetoresistance in an in-plane rotating magnetic field, we prove that, contrary to many accepted theoretical scenarios, the relative orientation between the two LCMO's magnetizations is not sufficient to determine the magnetoresistance. Rather the field dependence of magnetoresistance is explained by the interplay between the applied magnetic field and the (exponential tail of the) induced exchange field in YBCO, the latter originating from the electronic reconstruction at the LCMO/YBCO interfaces.