Enhancement of room temperature magnetoresistance in (1 − x)La0.67Sr0.33 MnO3/x Sb2O5 composites

Abstract

The electrical transport and magnetoresistance (MR) properties of the composites (1 − x)La0.67Sr0.33MnO3 (LSMO)/x Sb2O5 with different Sb2O5 molar percentages x were investigated. Experimental results show that the Sb2 O5 addition plays a key role in the electrical transport behaviour of the composites. Different transport and MR behaviours are observed for x ⩽ 2% and x⩾2%. Compared with pure LSMO, an enhanced MR effect for the composites is found over a wide temperature range under applied magnetic fields of both 0.3 and 3 T. Specially, a large and constant MR value of ∼18% is observed at room temperature, which is attractive for the study of applications. We argue that such an enhancement in MR is attributed to the magnetic disorder at the LSMO grain surfaces or boundaries caused by the Sb2O5 addition. Moreover, the resistivity (ρ) versus T curves for x = 1% and 2% samples fit well to the phenomenological model derived from spin-polarized tunnelling at grain boundaries and thermal activation. This result confirms that the grain boundaries have been modified in the composites with low Sb2O5 addition and provides information about the microscopic transport mechanism in the system.