Ab-initio theory of spin-phonon relaxation for paramagnetic defects in semiconductors

The theory of spin-lattice relaxation in solids were originally developed back in the 60's by pioneering work of Orbach [1] and various others. However, the ab-initio predictions for spin-phonon induced spin relaxation and dephasing are still a scarce. There are recent ab-initio studies [2] that discuss the spin-phonon interaction in molecular magnets with limited degrees of freedom, yet the ab-initio theory for paramagnetic defects in bulk materials is still lacking. Therefore, we will show the key elements of spin-phonon interaction in an exemplary nitrogen-vacancy (NV) center of diamond and depict the second-order Raman processes that governs the spin-lattice interaction within its |ms=0〉, |ms=±1〉 spin triplet manifold and also the main contributor in temperature dependence of zero-field splitting. We will show a novel spectral function formalism that incorporates both the continuous aspects of phonons and finite nature of point defects. In summary, our present method predicts spin T1 and T2 times for defects comparable to that of experiments [3].

[1] R. Orbach (1961) Spin-lattice relaxation in rare-earth salts. Proc. R. Soc. Lond. A264458–484

[2] A. Lunghi (2022) arXiv:2202.03776

[3] M. Cambria, G. Thiering et al., (2022). arXiv:2209.14446.