Ultrafast Magnetization Precession in Perpendicularly Magnetized L1_0-MnAl Thin Films with Co_2MnSi Buffer Layers

Perpendicularly magnetized L1_0-MnAl thin films with Co_2MnSi buffer layers were prepared on GaAs (001) substrates by molecular-beam epitaxy (MBE). The samples with high crystalline quality show a maximum uniaxial perpendicular magnetic anisotropy constant of 1.4\times 10^7 erg/cm^3. Ultrafast spin dynamics with a magnetization precession frequency up to 200 GHz was investigated by using time-resolved magneto-optical Kerr effect (TRMOKE) measurements, from which the Gilbert damping constant \alpha of epitaxial L1_0-MnAl thin films is evaluated to be less than 0.0175. This work provides an important reference for analyzing the current-induced magnetization switching process in MnAl-based spintronic devices.