September 2019

Researchers from Japan's National Institute for Materials Science (NIMS) have managed to introduce a quantum well structure into a conventional magnetic tunnel junction (MTJ). The researchers say that the QW structure can enhance the tunneling magnetoresistance (TMR) ratio by spin-dependent resonant tunnel (SDRT) effect, with a value of 1.5 times comparing with no SDRT case, at room temperature.

The researchers tell us that the key point of the QW formation is the band mismatch between Cr and Fe for majority band, and the mismatch-free Fe/MgAl₂O₄ interface. The finding is not just useful for enhancement of TMR ratio, it also provides a benefit that the TMR ratio could be kept almost constant in a wide bias voltage range of from -1V to 0.5V.

Researchers from the University of Groningen developed a two-dimensional spin transistor, in which spin currents were generated by an electric current through graphene. The device also include a monolayer transition metal dichalcogenide (TMD) that is placed on the graphene to induce charge-to-spin conversion.

Graphene is an excellent spin transporter, but spin-orbit coupling is required to create or manipulate spins. The interaction is weak in the graphene carbon atoms, but now the researchers have shown that adding the TMD layer increases the spin-orbit coupling.