Effect of intervening ferromagnet on spin accumulation in Py/Au/Py spin valve device

Nonlocal spin signal is largely dependent on the resistivity of nonmagnetic channel in spin valve devices. Since the resistivity of channel is subjected to change from sample to sample, it is necessary to keep the resistivity as constant as possible. Multiferromagnetic electrodes on single channel are favorable in order to minimize the variation of the resistivity. There is controversial that intervening ferromagnetic electrode may affect spin signal in such a structure. In this experiment, we fabricated Py/Au/Py spin valve devices with multi Py electrodes and measured series of nonlocal signal in various distances of Pys with or without intervening Py electrode aiming at clarifying the controversy.