Electrical-field-induced order transitions in Sr-doped manganite perovskites

Spin-dependent varistor-like electrical transport was observed in Sr-doped Nd2/3Sr1/3MnO3−δ perovskites for δ > 0.05, in which magnetic grain or phase boundaries is likely to be responsible. In addition to the varistor-like phenomena below a characteristic temperature, we also present evidence for electrical-field-induced magnetic order-order precursor transition at even lower temperature in regions close to highly insulating boundaries where larger electrical fields can be placed. This electrical-field-induced metamagnetic transition was understood by the competition among double exchange, superexchange interactions and external electrical or magnetic field.