Ultrafast photoinduced magnetization switching in magnetic heterostructures

Summary form only given. A problem of contemporary interest at both fundamental and applied levels concerns the ultimate speed "limit" for magnetization switching in magnetic storage media, typically composed of transition metal multilayers. It has been demonstrated recently how the absorption of light from fsec laser pulses in thin ferromagnetic metal layers can create a hot, excess electron spin population. Here we make use of such excitation by directly modulating an internal magnetic field which can be built into specific magnetic material heterostructures of contemporary interest in magnetoelectronics. In particular we demonstrate that ultrafast coherent magnetization rotation, in analog to Bloch equations of magnetic resonance, can be triggered by modulation of the exchange field which exists at the interface between magnetically coupled thin film bilayers with ultrashort laser pulses.