Figure 1

(a) Typical hysteresis curves for the ${\mathrm{Mn}}_{3-\delta }\mathrm{Ga}$ epitaxial film with $\delta =1.46$. (b) Schematic of the time-resolved magneto-optical Kerr effect measurement geometry. The applied magnetic field $H$ was directed at an angle ${\theta }_H$ with respect to the film normal. Spin precession occurs around the equilibrium angle $\theta$ of magnetization $M$. (c) Typical time-resolved Kerr signals for the $\delta =1.46$ film with different pump fluences $F_p$ at ${\theta }_H=80°$ and $H=10.4\mathrm{kOe}$. The solid curves show the fitted data. (d) Precession frequency $f$ and (e) inverse relaxation time $1/\tau$ for the films with $\delta =1.46$ (◯) and 0.88 (●) as functions of $F_p$. The dashed curves are visual guides only.Reuse & Permissions

Figure 2

Magnetic field angle ${\theta }_H$ variation of time-resolved Kerr signals in the epitaxial films of ${\mathrm{Mn}}_{3-\delta }\mathrm{Ga}$ with $\delta =1.46$ (a) and 0.88 (b), where the solid curves show the fit to the data. The data are shifted for clarity. The ${\theta }_H$ dependence of spin precession frequency $f$ (c), inverse relaxation time $1/\tau$ (d), and effective damping constant ${\alpha }_{\mathrm{eff}}$ (e). The open (filled) circles correspond to the data for $\delta =1.46$ (0.88). The solid curves through data points are model fits. The dashed lines in (e) show typical damping constants $\alpha$ for Fe, Co, and Ni [7].Reuse & Permissions

Figure 3

Theoretical calculations of (a) density of states and (b) damping constant $\alpha$ as a function of electron scattering frequency $\hslash /{\tau }_E$ in units of eV. (c) Theoretical calculations of damping constant with shifting Fermi energy ${ϵ}_F$ from $E_F$, based on the band structure corresponding to (a) with different band fillings. The $E_F$ is the Fermi energy corresponding to the valence electron number of Mn-Ga alloys. In (c), the calculation was performed at $\hslash /{\tau }_E=26\mathrm{meV}$ that corresponds to thermal broadening at 300 K. The thick (thin) curve corresponds to the data for stoichiometric and ordered $L{1}_0$ MnGa ($D{0}_{22}$ ${\mathrm{Mn}}_3\mathrm{Ga}$).Reuse & Permissions