Influence of the Interface on the Electric Control of the Magnetization Direction in Fe/PMN-PT Magnetoelectric Heterostructures

The magnetization direction of a ferromagnetic (FM) film deposited onto a ferroelectric (FE) substrate undergoes significant changes when it is subjected to applied electric fields. These are mainly due to the strain-mediated magnetoelectric effects associated with the FE switching behavior of the substrates. Here, we report on the magnetoelectric response of the magnetization direction at two different depths within the FM film in an artificial multiferroic heterostructure consisting of a 5 nm FM Fe film deposited onto a 0.7Pb­(Mg1/3Nb2/3)­O3-0.3PbTiO3 (PMN-PT) FE single-crystal substrate. The overall magnetic anisotropy of the Fe (5 nm)/PMN-PT system was studied by using magneto-optic Kerr effect (MOKE) magnetometry. On the other hand, the isotope-specific nuclear forward scattering (NFS) of synchrotron radiation was used to study the magnetization direction at two specific depths within the Fe film. Our results reveal that magnetic anisotropy is significantly influenced by the Fe/PMN-PT interface. Additionally, the magnetoelectric response of the easy magnetization direction when the layer is simultaneously subjected to electric and magnetic fields is different at (1st nm of Fe) as compared to away (3rd nm of Fe) from the Fe/PMN-PT interface. At the interface, the magnetization direction is influenced by the electric field-induced strain and charge effects originating in PMN-PT. Away from the interface, a weaker magnetoelectric response of the magnetization direction consistent with previous reports is observed. These results provide insight in understanding the magnetoelectric coupling behavior of such FM/PMN-PT heterostructures, which is crucial to recognize their potential in developing (multi)­functional devices based on such systems.