We report ultrafast transient‐grating measurements, above and below the Curie temperature, of the dilute ferromagnetic semiconductor (Ga,Mn)As containing 6% Mn. At 80 K (15 K), we observe that photoexcited electrons in the conduction band have a lifetime of 8 ps (5 ps) and diffuse at about 70 cm2/s (60 cm2/s). Such rapid diffusion requires either an electronic mobility exceeding 7700 cm2/V s or a conduction‐band effective mass less than half the GaAs value. Our data suggest that neither the scattering rate nor the effective mass of the (Ga,Mn)As conduction band differs significantly from that of GaAs.
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In calculations, we incorporate this heating by using electron temperature of 35 K (100 K) for measurements at lattice temperature of 15 K (80 K).
Diffusivity varies with , and the peaks of our grating will diffuse more rapidly than the troughs. Our numerical simulations indicate that for the densities and temperature used in this experiment, this effect can cause us to underestimate Da by up to 30%, making electron mobility potentially somewhat higher, but not lower, than the values we report.
mΩ cm at 15–35 K and 80–100 K; the range of temperatures reflects likely heating of electrons.
depends on p0 and the hole density of states, neither of which is accurately known. However, the effect of the holes on is less than 8% provided p0 exceeds 10 18 cm −3 and the hole effective mass exceeds 1/20 of the free‐electron mass.
