Large anisotropy of Gilbert damping constant in L2₁-ordered Co₂FeSi film

Abstract

We experimentally demonstrated anisotropic damping of the magnetization dynamics in a highly ordered Heusler compound Co3−xFexSi (x = 1.0, 2.0, and 3.0). The field-swept ferromagnetic resonance linewidth as a function of the resonant frequency was measured to exclude extrinsic contributions from two-magnon scattering and inhomogeneous line-broadening. In L21-ordered Co2FeSi film, a wide variation in the intrinsic Gilbert damping constant from 0.0023 to 0.0061 was clearly observed in the (111) plane, where a weak uniaxial magnetic anisotropy was formed via low-temperature epitaxial growth. The large anisotropy of the Gilbert damping constant was suppressed by increasing x, which suppresses the half-metallicity in Co3−xFexSi films.

Tunable magnetization relaxation of Fe2Cr1−xCoxSi half-metallic Heusler alloys by band structure engineering

“…6(a) and (c). Although the anisotropic extrinsic damping of FCCS appears universal in Hesuler alloys [29], when compared to Fe 2 CrSi and Fe 2 CoSi, is considerably lower and almost vanishes for 0.5 ≤ x ≤ 0.75.…”

“…However, except for a few Co-based Heusler alloys, the damping constant is larger than for Fe films (0.002), probably due to band broadening by structural defects, chemical disorder and magnon excitation [13,[24][25][26][27][28]. Furthermore, Heusler alloys usually exhibit large anisotropy in the ferromagnetic resonance (FMR) linewidth [26,29], which may lead to large variation in performance among devices. Therefore, tuning and reducing intrinsic damping, and a minimum extrinsic magnetic relaxation are required for reliable operations.…”

Low Gilbert damping in Co2FeSi and Fe2CoSi films

“…The very upper limit of the error margins was calculated assuming that the linewidth measured at 40 GHz is caused solely by Gilbert type damping. parameters from 0.0023 to 0.0061 for Co 2 FeSi films and 0.002 for Fe 2 CoSi [20]. In general, the Gilbert damping is expected to be low in half-metallic materials, where spinflip processes are suppressed [7,21].…”

Crystallographic anisotropy of the intrinsic Gilbert damping for single-crystalline Fe film

“…[26][27][28][29] From the difference in these frequency dependencies, we can evaluate those contributions independently. 21) ∆H eff was fitted by the linear function of f r as dashed lines in Fig. 9, and α int was estimated from the gradient of the dashed line.…”