Ultrafast inverse magnetostriction effect in Ni/Co ferromagnet

Abstract : Research upon femtosecond time resolved magnetic processes is part of the ultrafast optics branch known as femtomagnetism [Phys. Rev. Lett. 76, 4250 (1996)] where femtosecond laser pulses are used to switch the magnetisation of ferromagnetic materials. Another trend in modern ultrafast optics is driven by progress in picosecond ultrasonics – a well established research direction dealing with the generation of picosecond acoustic pulses by thermal expansion of acoustic transducers excited by femtosecond lasers [Phys. Rev. B 34, 4129 (1986)]. A novel concept envisioning control of magnetization in ferromagnetic materials on ultrafast timescales using acoustic pulses has been proposed very recently [Phys. Rev. Lett. 105, 117204 (2010); Phys. Rev. B 82, 104422 (2010)]. The results that will be presented combine femtomagnetism and picosecond ultrasonics in order to gain understanding on the inverse magnetostriction effect. Our experimental approach will show that by launching a picosecond phonon pulse through a ferromagnetic material it is possible to measure the phonon-spin interaction time.