Transition metal (TM) point defects in silicon carbide (SiC) have attracted special attention recently owing to their highly promising properties with respect to quantum technology applications. The paramagnetic electronic structure of these defects exhibits a rich set of interesting and not yet fully resolved physics. In particular, the character of wavefunctions and the corresponding strong electron-phonon coupling may highly influence their interaction with an external magnetic field. The complex interplay between the electronic orbitals, phonons and electron spin determines the effective pseudospin of the system that I demonstrate on vanadium and molybdenum defects in hexagonal silicon carbide (SiC) by means of ab initio calculations [1]. Furthermore, I show that this interaction leads to the experimentally already observed giant anisotropy in the g-tensor of the TM defects with Kramers doublet spin ground state, resulting in reduced and vanishing interaction with the magnetic field in parallel and transverse directions, respectively [1].

References:

[1] A. Csóré, A. Gali, arXiv:1909.11587v2 [quant-ph]