All-optical probe of sub-THz spin precession in a L1₀ MnGa nanolayer

We measured an all-optical time-resolved magneto-optical Kerr effect for L1₀ MnGa ultrathin films fabricated with a low-temperature hetero-epitaxy technique. Spin precession was observed with a frequency over 0.1 THz due to a large perpendicular magnetic anisotropy (PMA) field of ∼3 T. The effective Gilbert damping constant α _eff was sensitive to the deposition temperature. A minimum value of α _eff of 0.017 was observed, which was about twice as large as that reported for much thicker films of MnGa with high chemical ordering but was comparable to those reported in other nanometer-thick PMA material films.