Attosecond Magnetism

Ultrafast magnetism typically occurs when a magnetic system is irradiated by a short laser pulse, which deposits energy into the system. Subsequently, the system can demagnetize (due to a variety of physical mechanisms such as spin transfer, spin torques, spin-phonon couplings, etc.) on timescales as fast as few femtoseconds, and the electronic spin angular momenta can be deposited into the phononic bath. We are interested in exploring such phenomena, but starting from non-magnetic heavy materials with strong spin-orbit coupling, and while using intense laser pulses that induce highly-nonlinear optical responses. This allows pushing the speed of the magnetic response to the sub-femtosecond regime. We study the fundamental physical mechanisms allowing this response to arise, and develop ultrafast techniques for probing and controlling atto-magnetization. We are especially interested in possible ‘speed-limits’ for ultrafast magnetic responses.