<i>Ab initio</i> spin dynamics and spin-phonon relaxation in graphene multilayers

Spin dynamics in graphene and its multilayers is of high interest because of the tremendous potential graphene holds for spintronics and spin-qubits. Experimental observations demonstrate that relaxation lifetime and lifetime anisotropy show qualitatively different trends from single to bi-layer graphene. Several model-based theoretical studies suggest that these distinct trends have roots in interlayer coupling and substrate induced relaxation channels. However, it is not easy for these studies to handle these relaxation mechanisms realistically. To this front, we present our investigations of spin dynamics and in particular spin-phonon relaxation fully from first-principles in single and bi-layer graphene in the presence of an external electric field and/or hBN substrate. Using Lindbladian dynamics of density matrices[1], we conduct a systematic study of electron(hole) spins evolution for microseconds in these systems all the while fully accounting for their scattering against phonons. We predict that the interplay between interlayer coupling-induced spin-orbit field and the substrate phonons contribute to the observed spin dynamics in experiments.
[1] J. Xu et al, Nat. Commun. 11, 2780 (2020)