First-principles materials design for spin dynamics and transport

The realization of practical spintronic and spin-based quantum information technologies hinges on the design of materials that exhibit long spin lifetimes and coherent spin transport. Computational design of such materials requires parameter-free first-principles techniques to quantitatively predict spin dynamics and transport across a broad range of electronic structures, symmetries and dimensionalities, accounting for both coherent dynamics and incoherent scattering processes. We present a general formalism based on Lindbladian dynamics of first-principles density matrices to accurately calculate the intrinsic spin-phonon relaxation time of bulk materials, providing a unified treatment of the Elliott-Yafet (EY) and D'yakonov-Perel' (DP) mechanisms of spin relaxation. In addition to T1 spin relaxation times, we also demonstrate predictions of magnetic-field-dependent T2 and T2* times, separating decoherence and dephasing effects from first-principles simulations of Hahn echo measurements. Finally, we extend this modeling capability to first-principles density-matrix transport at device length scales within the Wigner function formalism. We elucidate the effects of realistic spin-orbit fields, such as Rashba fields and persistent spin helices, and the strength of scattering on spin transport in several materials. Overall, this general capability to predict complex spin dynamics and transport phenomena in arbitrary materials opens up the possibility for designing materials for spin-based devices.