{\textit{Ab initio} determination of pseudospin for paramagnetic defects in SiC

TL;DR

This paper uses ab initio calculations to determine the pseudospin and anisotropic magnetic properties of paramagnetic defects in SiC, revealing implications for quantum information applications.

Contribution

It provides the first ab initio analysis of pseudospin and g-tensor anisotropy in vanadium and molybdenum defects in SiC, linking electronic structure to magnetic behavior.

Findings

Giant anisotropy in the g-tensor of defects

Reduced magnetic interaction in certain directions

Implications for quantum information processing

Abstract

Paramagnetic point defects in solids may exhibit a rich set of interesting and not yet fully resolved physics. In particular, character of wavefunctions and electron-phonon coupling in these defects may highly influence their interaction with external magnetic fields. Complex interplay between the electronic orbitals, phonons and electron spin determines the effective pseudospin of the system that we demonstrate on vanadium and molybdenum defects in hexagonal silicon carbide (SiC) by means of \textit{ab initio} calculations. In this Rapid Communication, we find a giant anisotropy in the $g$-tensor of these defects with Kramers doublet spin ground state, resulting in reduced and vanishing interaction with the magnetic field in parallel and transverse directions, respectively. The consequences of our finding in the application of these defects for quantum information processing are briefly discussed.