Tuning Domain Wall Scattering in Manganite Microstructures with Electric Fields

Several hole-doped perovskite manganites, such as (La_1−y Pr_y )_1−xCa_xMnO₃ (LPCMO), exhibit electronic phase separation between ferromagnetic metallic (FMM) and charge-ordered insulating (COI) phases, yielding rich electronic and magnetic responses. Additional functionalities such as strain-induced uniaxial in-plane magnetic anisotropy (MA) have been observed in LPCMO thin films grown on (110) NdGaO₃ (NGO). In our prior work using anisotropic magnetoresistance (AMR), we found that MA weakens when films are cooled under stronger electric fields. Here we examine the low-field magnetoresistance (LFMR) of (La_0.4Pr_0.6)_0.67Ca_0.33MnO₃ (LP6CMO) and its role in the voltage dependence of AMR. Hall bars were patterned from 120 nm-thick LP6CMO films with channels of 120 μm × 20 μm and 240 μm × 40 μm. For current along the easy axis [1-10] direction, MR is linear when field and current are parallel (θ = 0^◦), becomes primarily quadratic near θ ∼ 80^◦, and is approximately linear at θ ∼ 90^◦. For current along the hard axis, MR is linear when field and current are perpendicular (θ = 90^◦) while for θ ∼ 0^◦, it is quadratic below ∼ 1000 G and crosses over to linear above ∼ 1000 G. The linear MR is due to suppression of spin fluctuations while the quadratic behavior is possibly due to domain rotation for magnetic fields aligned close to the hard axis. Our results show unique interplay between magnetic interactions and spin-orbit coupling in manganites which can be tuned using electric fields.