Magnetic field enhanced detection of coherent phonons in a GaMnAs/GaAs film

Ultrafast Optical Probe of Coherent Acoustic Phonons in Dirac Semimetal Cd3As2 Film Epitaxied on GaAs(111)B Substrate

“…In both the transient differential transmission (Δ T / T ) and differential reflectance (Δ R / R ) geometry of the pump–probe setup, the pump induced Δ T (Δ R ) signal oscillating at the phonon frequencies is detected as a function of delay time relative to the pump pulse. The ultrafast spectroscopy has been successfully used to study the coherent acoustic and optical phonons in various materials such as the thin-film structures, − bulk materials, ,− semiconductor superlattices, quantum wells, − two-dimensional (2D) materials, and heterostructures. , One of the mechanisms of coherent acoustic phonon generation and detection is the thermal strain induced by laser heating as proposed by Thomsen et al The optically pumped hot carriers promote a transient phonon temperature increase via the electron–phonon coupling within the illuminated area. This would give rise to a transient stress and a propagating strain wave (coherent longitudinal acoustic phonons) away from the sample surface at the speed of the longitudinal acoustic phonons.…”

Directly visualizing the crossover from incoherent to coherent phonons in two-dimensional periodic MoS2/MoSe2 arrayed heterostructure

“…Besides, direct visualization of incoherent and coherent phonon propagation can promote deeper understanding and design thermal management of PAHs. With the development of temporal and spatial resolution of the experimental techniques, several groups have detected coherent phonons under different additional conditions [21,22].…”