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Register a new userReexamination of the Elliott-Yafet spin-relaxation mechanism
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Hans Christian Schneider
Publication date
2015
fields
Physics
and research's language is
English
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We analyze spin-dependent carrier dynamics due to incoherent electron-phonon scattering, which is commonly referred to as Elliott-Yafet (EY) spin-relaxation mechanism. For this mechanism one usually distinguishes two contributions: (1) from the electrostatic interaction together with spin-mixing in the wave functions, which is often called the Elliott contribution, and (2) the phonon-modulated spin-orbit interaction, which is often called the Yafet or Overhauser contribution. By computing the reduced electronic density matrix, we improve Yafets original calculation, which is not valid for pronounced spin mixing as it equates the pseudo-spin polarization with the spin polarization. The important novel quantity in our calculation is a torque operator that determines the spin dynamics. The contribution (1) to this torque vanishes exactly. From this general result, we derive a modified expression for the Elliott-Yafet spin relaxation time.
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We extend our recent result for the spin-relaxation time due to acoustic electron-phonon scattering in degenerate bands with spin mixing [New J. Phys. 18, 023012 (2015)] to include interactions with optical phonons, and present a numerical evaluation of the spin-relaxation time for intraband hole-phonon scattering in the heavy-hole (HH) bands of bulk GaAs. Comparing our computed spin-relaxation times to the conventional Elliott-Yafet result quantitatively demonstrates that the latter underestimates the spin-relaxation time because it does not correctly describe how electron-phonon interactions change the (vector) spin expectation value of the single-particle states. We show that the conventional Elliott-Yafet spin relaxation time is a special case of our result for weak spin mixing.
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