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

Abstract

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 mΩ at the interface resistance of 1.7×10-1 Ω (µm)2. The spin diffusion length of Cu reaches 1.3 µm 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.