Electron spin decoherence due to phonons: Unified many-body framework and first-principles calculations

Spin-phonon (s-ph) decoherence governs the intrinsic limit of spintronic and quantum devices, so its understanding is a pressing matter in spin-based technologies. First-principles calculations enable precise predictions of s-ph interactions. However, understanding spin decoherence and relaxation due to phonons remains an open challenge. There are two main s-ph decoherence mechanisms – the Elliott-Yafet (EY) and D’yakonov-Perel’ (DP) – with distinct physical origins and theoretical treatments. Here we present a unified many-body approach for s-ph decoherence, which encompasses both the EY and DP mechanisms. Our method combines the ab-initio s-ph interactions with a diagrammatic approach to treat interacting spins. We apply our method to various centrosymmetric and noncentrosymmetric materials, where the EY and DP mechanisms are dominant, respectively. In both cases, our computed spin relaxation times are in excellent agreement with experiments. We provide evidence that our diagrammatic approach captures both the EY and DP spin decoherence, regardless of material symmetry. Our work demonstrates a widely applicable approach for quantitative analysis of spin decoherence for systems of interest in spintronics, quantum materials and quantum technologies.