Fig. 1: Schematic of the hexagonal boron nitride (hBN).
From: Spin defects in hBN as promising temperature, pressure and magnetic field quantum sensors
a Alternating boron (red) and nitrogen (blue) atoms and the lattice constants a and c. b Lattice contraction and expansion due to temperature variation, according to crystallographic data24. c cw ODMR spectra measured with (dark blue) and without (cyan) external magnetic field at different temperatures T = 295, 160, and 10 K. Lowering of the temperature causes the resonances \({\nu }_{0},{\nu }_{1}\) and \({\nu }_{2}\) to shift to larger microwave frequencies indicating an increase of the zero-field splitting \({D}_{{gs}}\).
