The field of spintronics involves the study of both spin and charge transportin solid state devices with a view toward increasing their functionality andefficiency. Alternatively, the field of ultrafast magnetism focuses on the useof femtosecond laser pulses to excite electrons in magnetic materials, whichallows the magnetic order to be dramatically changed on unprecedentedsub-picosecond time-scales. Here, we unite these two distinct researchactivities by using picosecond electrical pulses to rapidly excite electrons ina magnetic metal. We are able to deterministically and repetitively reverse themagnetization of a GdFeCo film with sub-10 picosecond electrical pulses. Themagnetization reverses in ~10ps, which is more than an order of magnitudefaster than any other electrically controlled magnetic switching. We attributethe deterministic switching of the magnetization to ultrafast excitation of theelectrons, a fundamentally different mechanism from other current drivenswitching mechanisms such as spin-transfer-torque (STT) or spin-orbit-torque(SOT). The energy density required for switching is measured and the process isfound to be efficient, projecting to only 4 fJ needed to switch a (20 nm)^3cell, which is comparable to other state-of-the-art STT-MRAM memory devices.This discovery will launch a new field of research into picosecond spintronicphenomena and devices.
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