Epitaxial growths and magnetization dynamics of Ni2MnSn Heusler alloy films

Abstract

Ferromagnetic resonance has been investigated in Ni2MnSn Heusler alloy films. The films were deposited at 673 < T < 723 K on MgO(001) substrates by means of magnetron sputtering. X-ray diffraction confirmed that the films were epitaxial. The films had magnetic parameters typical of bulk Ni2MnSn with L21 structural order. From angular dependences of the resonance field and the ferromagnetic resonance linewidth the intrinsic Gilbert contribution and extrinsic contribution to the ferromagnetic resonance linewidth due to two-magnon scattering were separated. Our data indicate a room temperature Gilbert damping of 0.007, which is comparable to that of half-metallic Heusler alloy. Surface roughness is responsible for a substantial extrinsic two-magnon contribution to the linewidth of the order of 50-300 Oe in these epitaxial soft magnetic Heusler alloy films. The spin wave stiffness of D = 70-100 meVÅ2 is one of the lowest for the known Heusler alloy.