Excitation of Coherent Spin Waves in GdFeCo film

Abstract

We present results of a time-resolved study of the ultrafast magnetic response of Gd_23.1Fe_71.9Co_5.0 MAMMOS structures under conditions near actual read/write temperatures. An all-optical pump and probe method was used in which an intense (pump) light beam excited a medium due to ultrafast laser heating and a less intense (probe) beam monitored this photo-excited state through the magneto-optical Kerr effect. Our experiment clearly demonstrates that the photo-excitation effectively excites coherent spin waves in the magnetic material. Precession frequencies of several GHz and relaxation times in the nanosecond range were observed.