Magnetic properties of NiMnSb(001) films grown on InGaAs/InP(001)

Abstract

NiMnSb half Heusler alloy films were prepared by molecular beam epitaxy ͑MBE͒ on InP͑001͒. The dc and rf magnetic properties were investigated by ferromagnetic resonance ͑FMR͒. The effective uniaxial anisotropy fields increased with increasing film thickness and reached nonzero asymptotic values. FMR linewidths rapidly increased with the film thickness due to the presence of two magnon scattering. Bulklike uniaxial anisotropies and two magnon scattering were caused by a self-assembled network of lattice defects. Gilbert damping parameter and spectroscopic g factor were found to be 3.1ϫ10 7 and 2.03, respectively, indicating a weak role of spin orbit interaction.

Optically induced magnetization dynamics and variation of damping parameter in epitaxialCo2MnSiHeusler alloy films

“…An alternative explanation of the variation of the value of ␣ may be provided by two-magnon scattering from a fourfold network of misfit dislocations, as reported previously for epitaxial thin films. 17,18 However, further structural studies are required to confirm the presence of such dislocations in the present case, and further theoretical work is required to demonstrate that this mechanism yields the correct dependence of ␣ upon the strength and orientation of the applied field. In those studies, the Fe films were subjected to a lattice strain by a mismatch with an underlying Pd layer, giving rise to dislocations with the same rotational symmetry as the Fe films.…”

“…Recent studies have shown that the damping of precessional dynamics in ferromagnetic metals can be complicated by the action of many extrinsic damping processes such as inhomogeneous broadening, 15 two-magnon scattering, [16][17][18] interface effects, 19 and spin diffusion into adjacent metallic layers, 14,15,20 with Cr in particular shown to be a strong spin scatterer. 21 Müller et al observed a sharp increase in the damping in CrO 2 films above a threshold pump fluence, possibly due to spin-wave instabilities.…”

Tunnel magnetoresistance effect and magnetic damping in half-metallic Heusler alloys

“…The deviation of the g value from 2, g-2, is roughly proportional to the spin-orbit parameter in the 3d-band, and is also related to the orbital magnetic moment, so that magnetic damping tends to decrease with decreasing orbital magnetic moment or average atomic number of elements included in ferromagnetic metals. Such discussions are given, together with experimental low damping constants observed in the NiMnSb half-Heusler alloy [10] and Fe-V binary alloys [12]. From observation of equation (3.2), magnetic damping can also vary with DOS.…”

“…Damping for various metals and alloys has been studied experimentally by several groups. It has been reported by these groups that very low damping constants can be exhibited in some Co-based Heusler alloys, half-Heusler alloys and iron-vanadium alloys [10][11][12][13]. In particular, Heusler alloys are very attractive materials because some have both small damping constants and very large spin polarization [14].…”

Spin dynamics in ultrathin film structures with a network of misfit dislocations

“…The angular dependence indicated that the defect lines in Fe͑001͒ were along the ͗100͘ crystallographic directions. We observed this type of two magnon scattering also in half metallic NiMnSb͑001͒ films 16 which were affected by two sets of rectangular lattice defects along the ͗100͘ and ͗110͘ directions. Consequently, the two magnon scattering was anisotropic, but did not disappear in any direction.…”