Magnetotransport properties of nano-constriction array in La 0.67Sr0.33MnO3 film

Abstract

Nano-constriction array in La0.67Sr0.33MnO 3 film was fabricated by using ion beam etching masked by a monolayer of packed and ordered array of SiO2 microspheres. Nano-constrictions of around 50 nm in width were fabricated. The low field magnetoresistance (LFMR) exhibited in the samples were observed to be current dependent and the I-V characteristics of the film were found to be nonlinear. These observations were attributed to the co-existence of the ferromagnetic regions and the nano-constricted region of weakened ferromagnetic coupling where Mn 3+-O-Mn4+ bond were distorted due to the ion beam bombardment. The spin polarized bias current would strengthen local ferromagnetic coupling when passing through this nano-constricted regions. This current effect is relatively large comparing to the external magnetic field to the drop of resistance.