Researchers from the Tokyo Institute of Technology have developed a new thin film material made from bismuth-antimony (BiSb) that is a topological insulator that simultaneously achieves a colossal spin Hall effect and high electrical conductivity.

This material could be used as the basis of spin-orbit torque MRAM (SOT-MRAM). SOT-MRAM SOT-MRAM can overcome the limitation of spin-transfer torque in MRAM memories - and provide a much faster, denser and much more efficient memory technology. Up until now, though, no suitable material that features both high electrical conductivity and a high spin hall effect was developed.

SOT-MRAM was recently demonstrated at imec, based on heavy metals which feature a low spin hall effect.

The new thin film achieves a colossal spin Hall angle of approximately 52, conductivity of 2.5 x 105 and spin Hall conductivity of 1.3×107 at room temperature. To create the films, the researchers used molecular beam epitaxy (MBE). The key factor behind the large spin hall effect could be a particular surface orientation named BiSb(012.

The researchers are now looking to collaborate with the industry and develop, test and scale-up BiSb-based SOT-MRAM.