Differentiation between strain and charge mediated magnetoelectric coupling in La_0.7Sr_0.3MnO₃/Pb(Mg_1/3Nb_2/3)_0.7Ti_0.3O₃(001)

Abstract

Magnetoelectric (ME) coupling in La0.7Sr0.3MnO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (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 Mn3O4 particles at the interface.

Strain and charge contributions to the magnetoelectric coupling in Fe3O4/PMN-PT artificial multiferroic heterostructures

“…Conversely, a positive voltage will lead to a depletion of electrons in magnetite and cause the magnetisation to increase. For other systems, such as the commonly investigated La 2/3 Sr 1/3 MnO 3 (LSMO), the effect of charge accumulation and depletion is opposite to the one discussed here, as the Mn-3d orbital is less than half filled for LSMO [39]. The polarisation coupling is dependent on the polarisation of PMN-PT with applied electric field and thus anti-symmetric regarding the sign of the electric field, in contrast to the strain coupling discussed above.…”

Elucidating proximity magnetism through polarized neutron reflectometry and machine learning

“…Neutron reflectometry facilitates structural characterization of multilayered materials by probing their nuclear and magnetic depth profiles at device-relevant spatial scales, enabling the study of hidden interfaces in a broad range of nanostructured and thin film systems. [1][2][3][4][5][6][7][8][9][10][11] Leveraging the interaction of spin-polarized neutrons with magnetic moments, polarized neutron reflectometry (PNR) is particularly well-suited to detecting magnetic interfacial phenomena, [12][13][14][15][16] such as the magnetic proximity effect. Proximity coupling to a magnetic material induces magnetic order near the interface of an otherwise non-magnetic system, making it a promising pathway for magnetizing topological insulators (TIs) without introducing magnetic dopants.…”

Electric Field Tuning of Magnetism in Fe3O4/Pt/PZN-PT Heterostructures Prepared by Atomic Layer Deposition

“…[5][6][7][8][9] Multiferroic heterostructures composed by ferromagnetic and ferroelectric phases are natively able to realize E-field controlling of magnetism attributed to the strain induced magnetoelectric (ME) coupling. [10][11][12][13][14] Motived by this idea, a series of cases have been explored to study the E-field manipulation magnetism, such as LSMO/PNN-PT, [15][16][17][18] YIG/PMN-PT [19][20][21] and Fe 3 O 4 / PZN-PT, 22 which verify the feasibility of E-field tuning ME coupling. However, most of these multiferroic heterostructures are prepared using physical methods by depositing ferromagnetic films directly on bulk single piezoelectric substrates, which is difficult to be integrated with traditional silicon-based semiconductor industry.…”