SiCCSi antisite pairs in SiC identified as paramagnetic defects with strongly anisotropic orbital quenching

The nearest-neighbor antisite pair defects in 4H-SiC, 6H-SiC, and 3C-SiC single crystals have been identified using electron paramagnetic resonance spectroscopy in combination with a nonperturbative ab initio scheme for the electronic g tensor. Based on the theoretical predictions, the positively charged defect has been found experimentally also in the cubic 3C-SiC polytype where it is characterized by spin 1/2 and highly anisotropic g values of g[subscript xx]=2.0030, g[subscript yy]=2.0241, and g[subscript zz]=2.0390 within C1[subscript h] symmetry. The exceptional large g values are explained by details of the spin-orbit coupling causing a strongly anisotropic quenching of the orbital angular momentum of the p-like unpaired electron.Deutsche Forschungsgemeinschaft (Grant No. GE 1260/3-1)Institut National de Physique Nucleaire et Physique des Particules/CNRSInstitut National de Physique Nucleaire et Physique des Particules/CNRS (IDRIS supercomputing center in Paris-Orsay Grant No. 061202