Spin dynamics of the antiferromagnetic-to-ferromagnetic phase transition in FeRh on a sub-picosecond time scale

The antiferromagnetic-to-ferromagnetic phase transition in FeRh films induced by heating with a femtosecond laser pulse was investigated using the time-resolved magneto-optical Kerr effect. An initial rise time of the magneto-optical signal of about 500fs is found as the FeRh is heated through the transition. The data offer a complementary view to previous pump–probe experiments on “simple” ferromagnetic materials and allow a glimpse at the complex interplay between lattice, electron and spin dynamics governing the first-order antiferromagnetic-to-ferromagnetic phase transition of FeRh.