Femtosecond laser induced magnetization dynamics in single nanomagnets

Here, we present magnetization dynamics measurements in 150nm thick Ni magnets with diameters from 5mum to 125nm by optical pump-probe technique. To the best of our knowledge this is the first ever report of magnetization dynamics study of single nanomagnets down to 125nm by the time-resolved magneto-optical technique. The combination of novel cavity enhancement of magneto-optical Kerr effect and 100 fs laser pulsewidth has allowed us to study the dynamics with a unique 100fs time resolution and 100nm spatial sensitivity.