Fig. 4: Pressure dependence of the zero-field splitting parameter Dgs/h.
From: Spin defects in hBN as promising temperature, pressure and magnetic field quantum sensors
a ODMR spectra of \({{{{\rm{V}}}}}_{{{{\rm{B}}}}}^{-}\) with microwave modulation (on/off) (blue) and sinusoidal magnetic field modulation (orange). The partially resolved hyperfine peaks are blurred due to an intentional overmodulation of the spectrum (for details see Supplementary Fig. 4) that allows a linear fit in the vicinity of the zero-crossings for a precise determination of the resonant transitions \({{{{\rm{\nu }}}}}_{1}\) (b) and \({{{{\rm{\nu }}}}}_{2}\) (c) and therefore the parameter \({{D}}_{{gs}}/{{h}}\). d \({{D}}_{{gs}}/{{h}}\) as a function of pressure, follows a slope of (1.16 ± 0.15) \({{{\rm{Hz}}}}/{{{\rm{Pa}}}}\) which is close to the expected value (0.91 ± 0.20) \({{{\rm{Hz}}}}/{{{\rm{Pa}}}}\) according to Eq. (15). Vertical error bars represent the standard deviations of the linear fits for \({{{{\rm{\nu }}}}}_{1}\)and \({{{{\rm{\nu }}}}}_{2}\) in panels (b, c). Horizontal error bars indicate the uncertainty of the determination of the sample area to which the pressure is applied.
