Anisotropic magnetoresistance in polycrystalline La_0.67(Ca_1−xSr_x)_0.33MnO₃

Abstract

Abstract We investigated the anisotropic magnetoresistance (AMR) effects in polycrystalline La 0.67 (Ca 1− x Sr x ) 0.33 MnO 3 . An anomalously large AMR of 19.1% was observed near the metal–insulator transition temperature ( T MI ) in polycrystalline La 0.67 Ca 0.33 MnO 3 , but slight Sr doping could significantly depress the anomalous AMR around T MI . By studying the temperature, magnetic field, current direction dependence of AMR and the phase transition process, it was suggested that the anisotropic spin-polarized transport and the demagnetization effect together with the metamagnetic transition around T MI play important roles in the anomalous AMR effects in polycrystalline perovskite manganites.