Enhanced magnetoresistance in La0.82Sr0.18MnO3-pi-conjugated semiconducting polymer heterostructure

We report a large enhancement (similar to 90%) in magnetoresi stance in La0.82Sr0.18MnO3 (LSMO) layers by incorporating a Tc-conjugated semiconducting polymer layer in between them. The epitaxial LSMO layers were deposited by DC magnetron sputtering on SrTiO3 single crystal substrates and have FM transition temperature (T-C) similar to 310 K. A semiconducting polymer poly(3-octylthiophene) (P3OT) layer was deposited over the epitaxial LSMO layer by solution dip coating technique and with subsequent deposition of another epitaxial LSMO layer, forming a LSMO-P3OT-LSMO heterostructure. The effect of P3OT incorporation on magnetotransport properties of this heterostructure has been examined in the temperature range 77-350 K. Large MR enhancement observed near room temperature in the FM regime is explained in terms of efficient magnetic field dependent carrier injection at LSMO/P3OT interface