Ultrafast spintronics with terahertz radiation*

To take advantage of the electron spin in future electronics, spin angular momentum needs to be transferred and detected. Heat gradients and electric fields have been shown to efficiently drive spin transport at megahertz and gigahertz frequencies. However, to probe the initial elementary steps that lead to the formation of spin currents, we need to launch and measure transport on femtosecond time scales. To achieve this goal, we transfer spintronic concepts to the terahertz frequency range by employing both ultrashort optical and terahertz electromagnetic pulses. This experimental strategy provides new insights into important transport phenomena, for instance the spin Seebeck effect as well as anisotropic and spin Hall magnetoresistance. Interesting applications such as the efficient generation of ultrashort terahertz electromagnetic pulses and the high-throughput characterization of spin-to-charge conversion emerge.