Spin-relaxation times exceeding seconds for color centers with strong spin-orbit coupling in SiC

TL;DR

This study demonstrates that certain color centers in SiC with strong spin-orbit coupling can have exceptionally long spin relaxation times exceeding seconds at low temperatures, promising for quantum tech applications.

Contribution

It reveals that specific crystal symmetry and spin-orbit interactions can suppress spin relaxation, leading to ultra-long spin lifetimes in SiC color centers.

Findings

Spin lifetime $T_1$ of 2.4 seconds at 2 K observed.

Strong spin-orbit coupling does not necessarily degrade spin coherence.

Crystal symmetry plays a crucial role in spin relaxation suppression.

Abstract

Spin-active color centers in solids show good performance for quantum technologies. Several transition-metal defects in SiC offer compatibility with telecom and semiconductor industries. However, whether their strong spin-orbit coupling degrades their spin lifetimes is not clear. We show that a combination of a crystal-field with axial symmetry and spin-orbit coupling leads to a suppression of spin-lattice and spin-spin interactions, resulting in remarkably slow spin relaxation. Our optical measurements on an ensemble of Mo impurities in SiC show a spin lifetime $T_1$ of $2,4$ s at $2$ K.