Computational study of skyrmion stability and transport on W/CoFeB.

Skyrmions are topologically protected magnetic structures originating from Dzyaloshinbskii-Moriya Interaction (DMI) which can be driven by a spin-polarized current making it a candidate for many different novel spintronic devices. However, the transport velocity is proportional to the size of the skyrmion rendering the effort of miniaturizing spintronics devices useless indicating that it is not possible to realise high-speed transport, small size and low operating current at the same time. One approach to solving the trilemma is to increase the spin Hall angle [Formula: see text], the conversion ratio between charge current and spin current, in the heavy metal layer. For example, beta-tungsten (β-W) has attracted attention due to its high spin Hall angle, abundance in nature and the potential to combine with other materials to form complex structures. To characterise the use of β-W as a heavy metal layer along with a CoFeB magnetic layer, the interfacial DMI and the external field required to generate skyrmions were estimated to be 1.5 [Formula: see text] and 0.1 T respectively, which were confirmed to be realistic. In that case, the about 10 nm diameter skyrmion was transported under SOT at a velocity of about 40 m/s, which has the potential for skyrmion-based unconventional computing devices like skyrmion race track memory and logic gate.