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In this work, pronounced oscillations in the time-resolved reflectivity of Heusler alloy Co_2MnAl films which are epitaxially grown on Ga As substrates are observed and investigated as a function of film thickness, probe wavelength,external magnetic field and temperature. Our results suggest that the oscillation response at 24.5 GHz results from the coherent phonon generation in Co_2MnAl film and can be explained by a propagating strain pulse model. From the probe wavelength dependent oscillation frequency, a sound velocity of(3.85±0.1)×10~3m/s at 800 nm for the epitaxial Co_2MnAl film is determined at room temperature. The detected coherent acoustic phonon generation in Co_2MnAl reported in this work provides a valuable reference for exploring the high-speed magnetization manipulation via magnetoelastic coupling for future spintronic devices based on Heusler alloy films.
In this work, pronounced oscillations in the time-resolved reflectivity of Heusler alloy Co_2MnAl films which are epitaxially grown on Ga As substrates are observed and investigated as a function of film thickness, probe wavelength, external magnetic field and temperature. Our results suggest that the Oscillation response at 24.5 GHz results from the coherent phonon generation in Co_2MnAl film and can be explained by a propagating strain pulse model. From the probe wavelength dependent oscillation frequency, a sound velocity of (3.85 ± 0.1) × 10 ~ 3m / s at 800 nm for the epitaxial Co_2MnAl film is determined at room temperature. The detected coherent acoustic phonon generation in Co_2MnAl reported in this work provides a valuable reference for exploring the high-speed magnetization manipulation via magnetoelastic coupling for future spintronic devices based on Heusler alloy films.