Theoretical model of the dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide

TL;DR

This paper presents a comprehensive theoretical model for the dynamic nuclear spin polarization mediated by paramagnetic point defects in diamond and silicon carbide, enhancing understanding of the microscopic processes involved.

Contribution

It introduces a unified theoretical framework that integrates multiple microscopic processes affecting optical DNP in diamond and SiC defects, aligning well with experimental data.

Findings

Electron spin coherence times are crucial for DNP efficiency.

Excited state lifetimes significantly influence nuclear polarization.

The model provides a deeper understanding of defect-based DNP mechanisms.

Abstract

Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point defects in semiconductors is a key resource for both initializing nuclear quantum memories and producing nuclear hyperpolarization. DNP is therefore an important process in the field of quantum-information processing, sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based spintronics. DNP based on optical pumping of point defects has been demonstrated by using the electron spin of nitrogen-vacancy (NV) center in diamond, and more recently, by using divacancy and related defect spins in hexagonal silicon carbide (SiC). Here, we describe a general model for these optical DNP processes that allows the effects of many microscopic processes to be integrated. Applying this theory, we gain a deeper insight into dynamic nuclear spin polarization and the physics of diamond and SiC defects. Our results are in good agreement with experimental observations and provide a detailed and unified understanding. In particular, our findings show that the defects' electron spin coherence times and excited state lifetimes are crucial factors in the entire DNP process.