Spin injection into multilayer graphene from highly spin-polarized Co2FeSi Heusler alloy

We demonstrate electrical spin injection into multilayer graphene (MLG) in a lateral spin valve device from a highly spin-polarized Co2FeSi (CFS) Huesler electrode. Exfoliated MLG was transferred onto prepatterned epitaxial CFS wires grown on an Si(111) substrate by a polymer-based transfer method. This method enabled us to fabricate multiple single-crystal CFS electrodes in contact with MLG. Electrical spin injection from CFS to MLG was detected through nonlocal magnetoresistance (MR) measurement. A nonlocal spin signal of 430 Ω was observed; this is the largest value among all reported nonlocal MR values in graphene-based devices.