Current-induced asymmetric transport in La_(0.8)Ca_(0.2)MnO_3 epitaxial thin films

摘要

We investigated the influence of a dc current on the transport properties in La_(0.8)Ca_(0.2)MnO_3 epitaxial thin films grown on SrTiO_3 substrates. A prominent finding is the appearance of asymmetric transport properties, like the behavior of p-n junctions, in a wide temperature range from 10 K to 300 K after the films were applied by a dc current over a threshold value. The asymmetric behavior resulted from a relative weak excitation is unstable and even spontaneously disappears. By optimizing excitation condition, the rectifyinglike behavior turns to be more significant and stable. Applying a small ac current could make the asymmetric transport collapse, subsequently, conventional symmetric transport behaviors appear. Phase separation and the coexistent ferromagnetic phases with different orbital order are taken into account in the interpretation of the observed phenomena.