Large Spin Accumulation with Long Spin Diffusion Length in Cu/MgO/Permalloy Lateral Spin Valves

We study the effect of interface resistance on the spin injection and detection efficiency in Cu/MgO/permalloy (Py) lateral spin valve devices. Insertion of the MgO layer enhances the spin accumulation by a factor of ten at 10 K: the maximum value is 10 m Omega at the interface resistance of 1.7 x 10(-1) Omega (mu m)(2). The spin diffusion length of Cu reaches 1.3 mu m at 10 K, which is twice larger than that of Ag/MgO/Py spin valves. As the interface resistance increases furthermore, the spin accumulation exponentially decreases. This can be explained by the large reduction of the spin polarization in the insulating layer. (C) 2011 The Japan Society of Applied Physics