Electric Field Effects on the Magnetic Anisotropy of Phase-separated Manganites

Several types of hole-doped perovskite manganites, such as (La_1−yPr_y)_1−xCa_xMnO₃ (LPCMO), have been observed to undergo an electronic phase separation between ferromagnetic metallic (FMM) and charge-ordered insulating (COI) phases. This property leads to a variety of fascinating electronic and magnetic phenomena. Of particular interest is the phenomenon of strain-induced uniaxial in-plane magnetic anisotropy (MA), which is generated when LPCMO thin films are grown on (110) NdGaO₃ (NGO) substrates. This study investigates if an external in-plane electric field can tune the magnetic anisotropy of such films. Hall bars were fabricated using photolithography on 120 nm thick LPCMO films, with channel dimensions of 120 μm × 20 μm and 240 μm × 40 μm. We mounted and wired our samples to 10.5 mm × 7.5 mm chip carriers and performed anisotropic magnetoresistance (AMR) measurements using a homemade apparatus with a large sample stage that can accommodate the chip carriers. Measurements were carried out in magnetic fields of 1 T and 2 T and at temperatures near the FMM percolation threshold (∼ 50 K). Our results suggest that with an electric field applied parallel to the magnetic easy axis during cool-down, the MA is reduced for higher electric fields. When the electric field is applied along the hard axis during cool-down, no significant electric field effect on MA was observed. Our data provide a novel method for controlling magnetic anisotropy of correlated electron materials using electric fields.