Electrical Control of Ultrafast Magnetic Speeds in Graphene Spin Field-Effect Junctions

Electric-field control of ultrafast magnetic processes is a key to low-energy, high-speed spintronics. The talk will describe graphene spin-field-effect junctions that enable gate-tunable superdiffusive spin transport across graphene-ferromagnet interfaces, providing an electrical knob for femtosecond magnetization dynamics. By electrostatically shifting the graphene Fermi level beneath a cobalt thin film, we tune interfacial spin-current transmission and thereby the laser-induced demagnetization time, reducing it from 203 fs (bare Co) to 93 fs, a more than 100% increase in the rate of magnetization quenching at fixed excitation. Superdiffusive-transport calculations reproduce the dependence on interface conductance and cobalt thickness, supporting a mechanism of enhanced angular-momentum transfer into graphene. The spin-field-effect junctions provide a route to gate-controlled ultrafast magnetic dynamics in device-relevant architectures.