Electric field induced changes in coercive field in thin film manganite microstructures

In hole-doped manganites such as (La_1-yPr_y)_1-xCa_xMnO₃ (LPCMO) there are multiple coexisting electronic phases, primarily the ferromagnetic metallic (FMM) phase and the charge ordered insulating (COI) phase. Additionally, in thin films of LPCMO grown on (110) NdGaO₃ (NGO) substrates, anisotropic strain produces uniaxial in-plane magnetic anisotropy. Together, these properties provide a unique opportunity to control magnetic behavior using in-plane electric fields. We used micrometer scale Hall bars of LPCMO thin films with channel dimensions 120 × 20 µm², 240 × 40 µm², and 540 × 100 µm² and a thickness of 120 nm to investigate the effect of electric fields on the micrometer scale FMM regions which coexist with the COI phase. By using a custom-built apparatus, we can perform planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) measurements on the Hall bars mounted on a chip-carrier. Using these techniques, we have found evidence indicating that cooling the LPCMO microstructures in an in-plane electric field reorganizes the FMM regions to reduce magnetic anisotropy and the coercive field. The electric field induced reduction in coercive field is observed for a range of temperatures which suggests that electric field is the primary driver of this phenomenon. We will discuss how these effects are results of the interplay between the intrinsic magneto-crystalline anisotropy and the electric field induced magnetic anisotropy leading to a novel form of magnetoelectric effect.