Linear Stark Splitting of Nuclear Spin Levels in GaAs

A quadrupole splitting of the fourfold-degenerate nuclear spin levels of ${\mathrm{Ga}}^{69}$, ${\mathrm{Ga}}^{71}$, and ${\mathrm{As}}^{75}$ in a single crystal of GaAs has been induced by the application of a dc electric field along the [111] direction. The splitting of the nuclear magnetic resonance has been observed and the coupling constants $R_{14}$ between the induced gradient tensor and the applied homogeneous electric field have been determined. The results are $R_{14}\left({\mathrm{Ga}}^{69}\right)=1.05\mathrm{}\times {10}^{10}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $R_{14}\left({\mathrm{Ga}}^{71}\right)=0.9\mathrm{}\times {10}^{10}$ ${\mathrm{cm}}^{-1\mathrm{}}$, and $R_{14}\left({\mathrm{As}}^{75}\right)=1.55\mathrm{}\times {10}^{10}$ ${\mathrm{cm}}^{-1\mathrm{}}$. A simple theoretical model explains the physical origin of this effect quite well.