Tunnel spin injection into graphene using Al2O3 barrier grown by atomic layer deposition on functionalized graphene surface

We demonstrate electrical tunnel spin injection from a ferromagnet to graphene through a high-quality Al2O3 grown by atomic layer deposition (ALD). The graphene surface is functionalized with a self-assembled monolayer of 3,4,9,10-perylene tetracarboxylic acid (PTCA) to promote adhesion and growth of Al2O3 with a smooth surface. Using this composite tunnel barrier of ALD-Al2O3 and PTCA, a spin injection signal of ∼30 Ω has been observed from non-local magnetoresistance measurements at 45 K, revealing potentially high performance of ALD-Al2O3/PTCA tunnel barrier for spin injection into graphene.

▸ Graphene spin-valve devices using Ni81Fe19/Al2O3 electrodes are fabricated. ▸ Atomic layer deposition (ALD) is used to fabricate Al2O3 tunnel barrier. ▸ Graphene surface is terminated with a 3,4,9,10-perylene tetracarboxylic acid (PTCA). ▸ Non-local magneto-resistance (MR) as large as 30 Ω is demonstrated. ▸ Tunnel spin injection into the graphene is achieved with ALD-grown tunnel barrier.