Giant fluctuations of local magnetoresistance of organic spin valves

Abstract We generalize the seminal Julliere formula for the tunnel magnetoresistance (TMR) of a spin valve to include the spin memory loss of an electron in course of travel between the electrodes. This generalized version applies locally and for arbitrary mechanism of the spin dephasing. On the basis of the generalized formula we demonstrate that the distribution of TMR along the surface of magnetized electrodes is very broad and includes the sign reversals.