Spin drift, spin precession, and magnetoresistance of noncollinear magnet-polymer-magnet structures

We present a theory to describe spin transport across a polymer sandwiched between magnetic contacts with arbitrary magnetization directions. We find that even a weak magnetic field can significantly modify spin transport in polymers through spin precession. It is shown that the interplay of spin drift (due to electric field) and spin precession can lead to damped oscillating magnetoresistance as the magnetic field increases. Our theory is used to explain the recently observed magnetoresistance and $I\text{‐}V$ characteristics in such organic structures. Potential device applications are discussed.