Differentiation between strain and charge mediated magnetoelectric coupling in La0.7Sr0.3MnO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3(001)

Abstract

Magnetoelectric (ME) coupling in La _0.7 Sr _0.3 MnO _3 /Pb(Mg _1/3 Nb _2/3 ) _0.7 Ti _0.3 O _3 (LSMO/PMN–PT (001)) has been probed in the past years to identify the underlying mechanism behind it. PMN–PT, which is well known for its excellent piezoelectric properties, also exhibits ferroelectricity. This motivates our interest to differentiate which effect is dominant for this ‘voltage control of magnetism’. Here, we present results for the ME coupling at different temperatures: 300 K and 80 K. In this article we discuss and explain, how the nature of ME coupling is influenced by different parameters such as magnetic field, electric field, directional dependence (hard axis, easy axis) and temperature. Owing to large lattice mismatch between LSMO and PMN–PT, the strain-mediated coupling is strongly prevalent, however the change in strain behaviour from butterfly loop to linear loop is observed as a function of temperature. ME measurements are performed along hard axis [100] and easy axis [110] of LSMO in the presence of remanent magnetic field which showcases the pure influence of electric field on the system, resulting in a combination of strain- and charge-mediated coupling. The magnetic depth profile is probed by polarized neutron reflectometry as a function of electric field which demonstrates the existence of an interlayer with reduced nuclear scattering length density and reduced magnetic scattering length density at the interface. From transmission electron microscopy, stoichiometric variations are observed due to the presence of Mn _3 O _4 particles at the interface.

Keywords

• magnetoelectric
• magnetism
• polarized neutron reflectometry
• transmission electron microscopy
• thin films