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

We report a large enhancement (∼90%) in magnetoresistance in La0.82Sr0.18MnO3 (LSMO) layers by incorporating a π-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 (TC)∼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.