  The electron spins of semiconductor defects can have complex interactions
with their host, particularly in polar materials like SiC where electrical and
mechanical variables are intertwined. By combining pulsed spin resonance with
ab-initio simulations, we show that spin-spin interactions within SiC neutral
divacancies give rise to spin states with an enhanced Stark effect, sub-10**-6
strain sensitivity, and highly spin-dependent photoluminescence with intensity
contrasts of 15-36%. These results establish SiC color centers as compelling
systems for sensing nanoscale fields.
