The theme will develop spin-orbit torque (SOT) materials based on thin films of Dirac and Weyl semimetals and three-dimensional topological insulators (TIs). These thin films will be grown by molecular beam epitaxy (MBE) and sputtering and will be combined with both metallic and insulating ferro/ferrimagnets (FMs) for the fabrication of high efficiency SOT devices such as nano-oscillators. The first task of the theme is devoted to the synthesis of thin films of Dirac semimetals (Cd₃As₂) and Weyl semimetals and their integration into heterostructures. This task will identify appropriate substrates and seed layers and develop growth protocols that produce single crystal wafer scale films using MBE and highly oriented wafer scale films by sputtering. The second task is devoted to the synthesis of thin films of three dimensional (3D) TIs. The resulting heterostructures will be patterned into SOT-based oscillators for different applications. The third task is to develop antiferromagnetic materials along with devices which rely on Néel ordering switching, and antiferromagnet domain wall motion will be fabricated.