Influence of the environment on the coherence properties of spin-defects in low-dimensional solids and nanostructures: a computational study

Several recent studies have shown that in three-dimensional materials (e.g. diamond and SiC), at low temperature and in the presence of a large magnetic field, the central spin decoherence is mainly due to the fluctuating magnetic field induced by nuclear spin flip-flop transitions. Hence the interaction between electronic defects with the nuclear spin bath of the crystal is the dominant one in determining spin-defect decoherence times. However, in the case of two-dimensional (2D) and nanostructured semiconductors, the interaction with the environment, for example a supporting subtract, is expected to significantly affect spin-coherence times. We present a computational study aimed at understanding environmental effects on coherent lifetimes of spin-defects. We evaluated coherence functions using the Cluster Correlation Expansion method, and we computed the Hahn-echo T₂ time – an important metric for qubit performance – for spin defects in 2D transition metal di-chalcogenides [1] interacting with various substrates, and for nanodiamonds with different surface terminations.

[1] Meng Ye, H. Seo, G. Galli. NPJ Comp. Mat. 5, 44 (2019)