Enhanced spin accumulation at room temperature in graphene spin valves with amorphous carbon interfacial layers

TL;DR

This study shows that adding an amorphous carbon layer at the ferromagnet-graphene interface significantly boosts spin accumulation at room temperature, with enhancements up to 10,000 times, enabling high current densities without degradation.

Contribution

It introduces a method of using electron-beam induced amorphous carbon layers to greatly enhance spin accumulation in graphene spin valves at room temperature.

Findings

Spin accumulation enhanced by up to 10^4 times with amorphous carbon layers.

Large spin accumulations exceeding 500 microeVs achieved at room temperature.

Amorphous carbon interface withstands high current densities without degradation.

Abstract

We demonstrate a large enhancement of the spin accumulation in monolayer graphene following electron-beam induced deposition of an amorphous carbon layer at the ferromagnet-graphene interface. The enhancement is 10^4-fold when graphene is deposited onto poly(methyl metacrylate) (PMMA) and exposed with sufficient electron-beam dose to cross-link the PMMA, and 10^3-fold when graphene is deposited directly onto SiO2 and exposed with identical dose. We attribute the difference to a more efficient carbon deposition in the former case due to an increase in the presence of compounds containing carbon, which are released by the PMMA. The amorphous carbon interface can sustain very large current densities without degrading, which leads to very large spin accumulations exceeding 500 microeVs at room temperature.