Low field magneto-transport in LBSMO–PMMA composite

The low field magneto-transport has been measured as a function of temperature in the range 77–300 K and magnetic field; H⩽3.6 kOe for La0.7Ba0.2Sr0.1MnO3 (LBSMO)–x wt% PMMA composites where x=0, 2, 6 and 10. The X-ray diffraction (XRD) study reveals that no structural modification has occurred in the LBSMO in the composite. Scanning electron microscopy (SEM) investigation shows PMMA getting dispersed through the sample volume and some LBSMO grains appear to be coated with the polymer. The metal-like transition observed at ∼150 K in the virgin LBSMO sample disappears in the composite samples and the resistance shows an increase of about three orders of magnitude as the polymer concentration is increased to 10 wt%. Despite this huge increase in the resistance, the low field magneto-resistance (LFMR) shows an enhancement although smaller than the values commonly observed for other manganite-polymer composite systems. Spin polarized tunneling that causes LFMR seems to be enhanced in the composites.