Kavli Affiliate: Daniel C. Ralph
| First 5 Authors: Yongjian Tang, Yongjian Tang, , ,
| Summary:
Spin Hall magnetoresistance (SMR) measurements provide a way to probe the
surface spin structure of insulating magnetic materials. Such measurements
produce resistance signals of the form $Delta$R $propto$
cos[2($alpha$-$alpha$$_0$)], where $alpha$ is the angle between the current
and the external in-plane magnetic field. Previous experiments on a wide range
of materials have found $alpha$$_0$ = 0$deg$ for ferromagnets and
$alpha$$_0$ = 90$deg$ for antiferromagnets. Here we investigate SMR in
bilayers of Pt with monodomain BiFeO$_3$ multiferroic epitaxial thin films. We
observe signals of the form $Delta$R $propto$
cos[2($alpha$-$alpha$$_0$)] but surprisingly the angle $alpha$$_0$ can take
values very different from 90$deg$ or 0$deg$, with large variations from
sample to sample. The aim of the paper is to report this striking departure
from the expected magnetic field dependence of SMR and to encourage
consideration of possible microscopic mechanisms.
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