Magnon excitations in ferromagnetic monolayers

 Examples of our recent work are the studies of Fe and Co monolayers grown on different metallic substrates [1-3]. The magnon dispersion relation and lifetime is measured over the whole surface Brillouin zone (see Fig. 2 (a)). 

Fig. 2: (a) Magnon dispersion relation of 1 and 2 ML Fe films grown on W(110) measured along the direction of the (110) surface Brillouin zone. (b) Evolution of the magnon wave-packets in real time and space (results of the 2 ML sample at 0.7 Å−1 and 82 meV).

Using a two-dimensional Fourier transform, one can provide a real time and space representation of magnons. The evolution of the magnon wave-packets excited at a wave-vector of 0.7 Å−1 on a 2 ML Fe/W(110) film is shown in Fig. 2 (b). Our results reveal that the high wave-vector magnons are strongly confined in time as well as in space [4].