Magnetic Anisotropy, Anisotropic Magnetoresistance, and Planar Hall Effect in Phase-Separated (La_1-yPr_y)_1-xCa_xMnO₃ Thin Films

Phase competition between the ferromagnetic metallic (FMM) and charged order insulating (COI) phases of the perovskite manganite (La_1-yPr_y)_1-xCa_xMnO₃ (LPCMO) has led to the observation of unique electronic and magnetic properties. In addition, the coupling between its electronic and magnetic properties give rise to the possibility of tuning its magnetic properties, such as magnetic anisotropy, using electric fields. Thin films of (La_0.5Pr_0.5)_0.67Ca_0.33MnO₃ were grown on (110) NdGaO₃ (NGO) using pulsed laser deposition to investigate these phenomena. The NGO substrate exerts anisotropic in-plane strain which results in uniaxial, in-plane magnetic anisotropy and a single-domain to multi-domain transition in the FMM regions as they percolate at low temperatures. We observed anisotropic magnetoresistance (AMR) associated with the magnetic anisotropy at low magnetic fields. Measurements at higher magnetic field showed a reduction in the AMR, which suggests a combined effect of both magnetic anisotropy and phase separation. The planar Hall effect (PHE) in these samples enabled us to measure the voltage dependence of magnetic anisotropy due to electric field induced dynamic percolation.