Nuclear acoustic resonance ofGe73in single-crystal germanium; interpretation of experimental gradient-elastic-tensor components in germanium and zinc-blende compounds

Nuclear acoustic resonance (NAR) has been used to study the ${}_{}{}^{73}{}_{}{}^{}\mathrm{Ge}$ linewidth and shape in Ge single crystal and to measure the nonzero components $S_{11}$ and $S_{44}$ of the tensor $S$ which relates elastic strain to electric field gradients at the ${}_{}{}^{73}{}_{}{}^{}\mathrm{Ge}$ nuclear position. The ${}_{}{}^{73}{}_{}{}^{}\mathrm{Ge}$ $\Delta m=\pm 2$ NAR at 300 K and 20 MHz for magnetic field in the [110] direction has a Gaussian line shape and a second moment of 0.034 ${\mathrm{G}}^2$ explainable as the sum of dipole-dipole and pseudoexchange contributions. Ge, III-V—, and I-VII-compound $S_{11}$ values are shown to be proportional to the first-neighbor ion contribution calculated for each different nuclear position. The required first-neighbor charge indicates homopolar bonding for Ge and the III-V compounds and heteropolar bonding for the I-VII compounds. Ge and the III-V—compound $S_{44}$ values are shown to be approximately proportional to $〈r^{-3\mathrm{}}〉$ for the $p$ electron in the hybrid bonds.