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leftbank007
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for example, in GaAs, the LA phonon lifetime can be ~850 ns, while LO phonon lifetime is only about 5 ps. Why such huge difference occurs? Thanks!
Acoustic and optical phonons are two types of lattice vibrations in a solid material. Acoustic phonons are associated with the propagation of sound waves, while optical phonons are associated with the absorption or emission of light.
This is because acoustic phonons have lower energies and longer wavelengths compared to optical phonons. This results in weaker interactions with the surrounding lattice, leading to a longer lifetime.
The lifetime of acoustic phonons can be affected by various factors such as temperature, impurities, defects, and crystal structure. These factors can influence the strength of the interactions between the acoustic phonons and the lattice, affecting their lifetime.
The longer lifetime of acoustic phonons allows them to travel longer distances before scattering, resulting in a higher thermal conductivity of the material. This is because acoustic phonons are responsible for the transfer of heat through a material.
Yes, the lifetime of acoustic phonons can be modified by altering the factors that affect their interactions with the lattice. For example, adding impurities or defects to a material can decrease the acoustic phonon lifetime, leading to a decrease in thermal conductivity.