Low-field magneto-resistance of spray pyrolysis deposited La0.67Ca0.33MnO3 thin films

摘要

The magnetoresistive behaviour of La0.67Ca0.33MnO3 thin films deposited by ultrasonic spray pyrolysis on YSZ substrate has been investigated at low applied de magnetic fields. The highest magneto-resistance ratio (MR) of -17.75% has been observed at 77 K for applied de magnetic field, H-dc = 3 kG. The variation of the MR with temperature has been investigated and it has been observed that at lower temperatures the increase in MR is very rapid. This MR-T behaviour shows that the magneto-resistance has its origin in the grain boundaries. The variation of the MR with H-dc shows a faster increase in the MR at lower applied de fields. Surface morphological explorations employing scanning electron microscopy show the presence of microcracks throughout the films surface and also that these films are micro-crystalline, having an average grain size of similar to 125 nm. [References: 24]