Spin centres in SiC for all-optical nanoscale quantum sensing under ambient conditions

Level anticrossing (LAC) spectroscopy has been demonstrated on a family of uniaxially oriented spin color centers with $S = 3/2$ in the ground and excited states in hexagonal $4$H-, $6$H-, and rhombic $15$R-SiC polytypes. It has been shown that these centers exhibit unique characteristics such as optical spin alignment up to the temperatures of $250^\circ$C. A sharp variation of the IR photoluminescence intensity in the vicinity of LAC with the record contrast has been observed, which can be used for a purely all-optical sensing of the magnetic field and temperature without applying radiofrequency field. A distinctive feature of the LAC signal is weak dependence on the direction of the magnetic field that allows one to monitor the LAC signals in the nonoriented systems, such as powder of SiC nanocrystals.
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