Spin-obit torque heterostructures based on topological insulators and 2D materials

In recent years, spintronics has seen a substantial increase on application in data storage devices, targeting low-energy cost and non-volatility.

Indeed, the magnetic random access memory (MRAM) is the only non-volatile memory capable of high-density, high-endurance and fast-write operation and is considered as the best candidate for embedded non-volatile applications. In this technology, the information is stored by the direction of the magnetization of ferromagnets.

The most scalable and efficient way to control the magnetization is the use of spin currents, which exert a torque on it and can fully reverse its direction.

The most common spin-sources investigated for spin-orbit-torque MRAM (SOT-MRAM) are heavy metals such as Pt, W or Ta, which convert an electrical current in a spin current by means of, for example, the spin Hall effect arising from their strong spin-orbit coupling.

The reported SOT efficiencies indeed allow current-induced magnetization switching, however, the current densities required are still too large for practical implementations.Steady progress in two-dimensional materials (2DMs) offers new perspectives for downscaling and improving MRAM performance.

Their 2D nature and weak van-der-Waals interaction between layers enables to create atomically thin stacks with sharp interfaces, circumventing roughness and inter-diffusion, which significantly degrade the spin properties of conventional materials.

Among them, topological insulators and transition metal dichalcogenides are expected to be very efficient spin-sources that could significantly enhance the SOTs in comparison to conventional bulk materials.

The SORTIR project therefore aims at using the unique properties of 2DMs to unleash their potential for high SOT efficiencies, targeting both low-consumption and high density for data storage.