Spin-Phonon Interactions and Spin Decoherence from First Principles

Citation

Park, Jinsoo (2022) Spin-Phonon Interactions and Spin Decoherence from First Principles. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/80bd-x991. https://resolver.caltech.edu/CaltechTHESIS:06052022-215214933

Abstract

Developing a microscopic understanding of spin decoherence is essential to advancing quantum technologies. Electron spin decoherence due to atomic vibrations (phonons) plays a special role as it sets an intrinsic limit to the performance of spin-based quantum devices. Two main sources of phonon-induced spin decoherence, the Elliott-Yafet (EY) and Dyakonov-Perel (DP) mechanisms, have distinct physical origins and theoretical treatments. First-principles calculations of electron-phonon (e-ph) interactions combined with many-body perturbation theory are promising to study phonon-induced spin decoherence. However, predicting the spin response in materials remains an open challenge; methods for quantifying spin-dependent e-ph interactions in materials, as well as a linear response framework for spins in the presence of e-ph interaction is missing. In this thesis, we provide a first-principles framework for computing the relativistic spin-dependent electron-phonon interactions. We develop a formalism that unifies the modeling of EY and DP spin decoherence, and provide a rigorous many-body perturbation theory for obtaining the spin-spin correlation function including the vertex corrections due to e-ph interactions. We compute the phonon-dressed vertex of the spin-spin correlation function with a treatment analogous to the calculation of the anomalous electron magnetic moment in QED. We find that the vertex correction provides a giant renormalization of the electron spin dynamics in solids, greater by many orders of magnitude than the corresponding correction from photons in vacuum. We further identify the long-range quadrupole e-ph interaction in materials, and demonstrate its importance in the description of phonon-induced spin decoherence. We show first-principle calculations of spin-dependent e-ph interactions in correlated electron systems, using the framework of Hubbard-corrected density functional theory. Lastly, we provide technical details in the implementation of ab-initio e-ph interaction in PERTURBO, a software package for first-principles calculations of charge transport, spin dynamics, and ultrafast carrier dynamics in materials. In summary, the thesis demonstrates a general approach for quantitative analysis of spin decoherence in materials, advancing the quest for spin-based quantum technologies.

Thesis Files