Gilbert magnetic damping constant of epitaxially grown Co-based Heusler alloy thin films

The magnetic damping constant in a series of Co₂ MnAl _x Si_1-x and Co₂ Fe_x Mn_1-x Si Heusler alloy epitaxial films were systematically investigated by using ferromagnetic resonance technique. The determined magnetic damping constant is roughly proportional to the density of states at the Fermi energy of the first principle calculation. The result is consistent with the theoretical prediction when taking spin-orbit interaction into account. The small Gilbert damping constant for the fabricated films other than the Co₂ Fe_x Mn_1-x Si film with x>0.6 can be originated in the half-metallic electronic structure of Heusler alloys.