Researchers design novel graphene-based spin valve that relies on van der Waals magnet proximity

A team of researchers from CIC nanoGUNE, IKERBASQUE, IMEC and CNRS have reported a spintronic device that leverages proximity effects alone, specifically a 2D graphene-based spin valve. The functioning of this valve relies only on the proximity to the van der Waals magnet Cr₂Ge₂Te₆. Spin precession measurements showed that the graphene acquires both spin–orbit coupling and magnetic exchange coupling when interfaced with the Cr₂Ge₂Te₆. This leads to spin generation by both electrical spin injection and the spin Hall effect, while retaining spin transport. The simultaneous presence of spin–orbit coupling and magnetic exchange coupling also leads to a sizeable anomalous Hall effect.

The primary objective of this recent study was to tackle a long-standing research challenge, namely that of realizing the first-ever seamless 2D spintronic device. The spin valve they developed could enable the manipulation and transport of spin entirely in the 2D plane.

The team explained that the device consists of a single piece of graphene, locally functionalized by the proximity effect using the van der Waals magnetic insulator Cr₂Ge₂Te₆. Two functionalized graphene regions act as the spin injector and detector, while the pristine section in between serves as the spin transport channel.

The spin valve introduced by the researchers has a key advance over previous designs, namely the lack of physical interfaces between its components. The absence of these interfaces can reduce the loss of spins, improving the device's performance.

The team's experiments revealed that proximitized graphene, the central component of this all-2D spin valve, exhibits a coexistence of spin-orbit and magnetic proximity effects. The seamless structure demonstrates the feasibility of using the proximity effect to develop essential electronic devices.

In initial tests, the team's 2D graphene spin valve achieved very promising results, exhibiting spin-orbit and magnetic exchange coupling simultaneously, which contributed to a sizeable anomalous Hall effect. This recent study could pave the way for developing a new kind of highly efficient spintronic device, which the team refers to as "proximitronics."