Spin-polarized quantum point contacts for efficient spin injection in graphene

SPICE Young Research Leaders Group Workshop: Magnetism in van der Waals materials: current challenges and future directions, July 8th - 10th 2025

Josep Ingla-Aynés

The realization of functional graphene-based spintronic devices relies on the ability to efficiently inject and detect spins. Typical injection and detection efficiencies are of the range of 10%, resulting in a spin signal which, in the best-case scenario (no spin relaxation), is only 1% of the device resistance. For this reason, seamless approaches have been pursued to inject spins from the graphene channel itself by proximity coupling to other materials. I will present new results on quantum point contacts that are electrostatically defined in bilayer graphene and, by the application of moderate out-of-plane magnetic fields of less than one tesla, become valley and spin polarized. Based on these results I will discuss the possibility of injecting spins in bilayer graphene using such devices and the advantages and drawbacks of this approach when compared to other existing approaches such as spin-orbit or magnetic proximity.