Optical Phonons in Electron Spin Relaxation

Abstract

An approximate dispersion curve for the optical branch of the lattice vibration is used to estimate the spin-lattice relaxation time attributed to optical phonons. The relaxation rate is found to be ${T_1}^{-1\mathrm{}}\propto \exp (-\frac{\hslash {\omega }_{0j}}{\mathrm{kT}})$, where ${\omega }_{0j}$ is an optical-phonon frequency at k=0. It is also found that if the band-width of the optical mode is narrow, if the optical-phonon energy is low, and if the lattice vibration is even, then the spin-optical phonon relaxation process can dominate the conventional acoustical processes. The applications of the theory to some experimental results are also discussed.