Spin decoherence and dephasing in crystals from first principles

Advances in spintronics and spin-based quantum information applications require a precise understanding of electron spin dynamics in condensed matter systems. Spin dynamics is typically characterized by time scales T₁ for relaxation, T₂ for decoherence and T₂^* for decoherence including inhomogeneous broadening induced spin dephasing. While these time scales are measured experimentally and estimated from model spin Hamiltonians, predicting them from first principles to identify the limiting spin properties of new materials has remained a challenge. Here, we present direct real-time simulations of Hahn spin echo measurements using a first-principles density-matrix dynamics approach. We investigate a range of systems spanning from semi-metallic graphene to halide-perovskite semiconductors and distinguish between T₂ and T₂^* from the spin-echo simulations. We show that the impact of Lande g-factor fluctuations on dephasing in the intrinsic spin-phonon dynamics varies dramatically across systems of varying electronic structure, symmetry, and dimensionality.