Spintronic Terahertz Emitters in Silicon-Based Heterostructures

Integration of active elements into silicon wafers is the first step towards their usage in modern electronic devices based on nanometric structures. Spintronic terahertz emitters, typically composed of nanometer-thin magnetic multilayer, have the outstanding capability of producing high-quality, broadband terahertz pulses using extremely simple heterostructures. A question remains on whether an efficient and cheap integration with other silicon-based technologies can be achieved. We show here that simply having a ferromagnetic layer on silicon produces remarkably efficient spintronic terahertz emission despite the low spin-orbit coupling of the individual components. We achieve this by leveraging on the natural formation of silicides at the interface of a transition metal and silicon. The cobalt silicide layer has good spin-to-charge conversion efficiency that reaches around 1/6 as that of the prototypical spintronics THz-emitter heterostructure cobalt/platinum.