Pulsed Field Measurements of Large Zero-Field Splittings: V3+ in Al2O3

Abstract

Use of pulsed magnetic fields for determining large zero-field splittings of paramagnetic ions is considered. Measurements of zero-field splittings of over 50 ${\mathrm{cm}}^{-1\mathrm{}}$ are feasible; a numerical example for $S=1\mathrm{}$ is discussed in order to indicate the present range and limitations of the method. The method is applied to measurements of the zero-field splitting of ${\mathrm{V}}^{3+}$ in ${\mathrm{Al}}_2$ ${\mathrm{O}}_3$ at 4.2°K and 1.5°K. Assuming $g_{\parallel }=1.92\mathrm{}$, $D=7.85\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$ was determined from experiments with 4 mm and 8 mm wavelength radiation and pulsed magnetic fields of the order of 100 kilogauss. The magnitude and sign of $D$ are in good agreement with earlier estimates from optical and microwave measurements.