2024/08/22 by Junqing Xu, Xu, Junqing · 2 citations
Materials Science · #Computational Physics (physics.comp-ph) #FOS: Physical sciences #Graphite, nuclear technology, radiation studies #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · pdf · doi:10.48550/arxiv.2408.12054
openalex publication_date 2024/08/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We predict "intrinsic" spin relaxation times (T1) of graphite due to spin-orbit-phonon interaction, i.e., the combination of spin-orbit coupling and electron-phonon interaction, using our developed first-principles density-matrix approach. We obtain ultralong T1, e.g., ∼600 ns at 300 K, which leads to ultralong in-plane spin diffusion length ∼110 μm within the drift-diffusion model. Our prediction sets the upper bound of T1 of graphite at each given temperature and Fermi level. The anisotropy ratios of T1 or values of T1z/T1x are found small and around 0.6. We examine the applicability of the well-known Elliot-Yafet (EY) relation, which declares that spin relaxation rate T1α-1 (α=x,y,z) is proportional to the product of the ensemble average of spin mixing parameter ⟨ bα2⟩ and carrier relaxation rate τp-1. Our numerical tests suggest that the EY relation works qualitatively if the degeneracy threshold tdeg for evaluating bα2 is elatively large (not much smaller than or comparable to kBT), e.g., 10-3 eV or larger, but fails if tdeg is too tiny (much smaller than kBT), e.g., 10-6 eV or smaller.