Ozbay, A., Nowak, E. R., Yu, Z. G., Chu, W., Shi, Y., Krishnamurthy, S., … & Newman, N. (2009). Large magnetoresistance of thick polymer devices having La 0.67 Sr 0.33 MnO 3 electrodes. Applied Physics Letters, 95(23), 232507.
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 0.4𝜇m0.4 μm, respectively. The spin transport coherence length is enhanced by the electric field, leading to an enhancement in MR with increasing applied voltage.
This work was supported by ONR under Contract No. N00014-07-C-0393. E.R.N. also acknowledges partial support by DOE under Award No. DE-FG02-07ER46374 and thanks G. Szulczewski for many stimulating discussions.