Large magnetoresistance of thick polymer devices having La0.67Sr0.33MnO3 electrodes.

We report magnetoresistance (MR) measurements for structures with micrometer-thick regioregular, polythiophene (rr-P3HT) polymer layers between two ferromagnetic contacts. Hole spin transport through the polymer layer leads to a relative MR value in 300 mT fields of 0.3% at 300 K and increasing to 18% at 25 K. The inferred intrinsic spin lifetime and diffusion length are about 7 ms and 0.4 μm, respectively. The spin transport coherence length is enhanced by the electric field, leading to an enhancement in MR with increasing applied voltage. [ABSTRACT FROM AUTHOR]