Nuclear acoustic resonance (NAR) and nuclear magnetic resonance (NMR) are used to study the linewidths, second moments, and line shapes of nuclear-spin systems of InAs, InSb, GaAs, GaSb, and AlSb. These cw measurements are made at frequencies of 8-10 MHz and at 300 °K in single crystals with intrinsic or near intrinsic concentrations of impurities. Different NAR and NMR linewidths for the same nuclear-spin system are explained by the different interaction Hamiltonians for spin-phonon and spin-photon couplings to the nuclear-spin system. When the magnetic field is along (001) directions, the resonance line shapes are broadened by dipole-dipole and isotropic nuclear-exchange interactions. When the magnetic field is rotated from (001) directions, increased broadening of the resonance line shapes is explained by small anisotropic dipole-dipole and much larger anisotropic quadrupole interactions. The measured like-spin and unlike-spin exchange constants agree with an exchange-constant dependence on the inverse fourth power of the internuclear distance. Like-spin and unlike-spin exchange constants are determined at the nuclear positions in each compound and used with a theory for indirect nuclear-spin exchange to predict the ^-character electronic wave-function density. The strongly anisotropic quadrupole broadening is explained by electric field gradients produced by the electric fields associated with ionized substitutional impurities. From the measured field gradients, antishielding constants at the In, Sb, Ga, and As nuclear positions are determined relative to each other. 9 R. M. Sternheimer, Phys. Rev. 146, 140 (1966).

Nuclear-acoustic-resonance determinations are made of the magnitudes and relative signs of the two different nonzero components S» and S44 of the fourth-rank tensor relating electric field gradients to elastic strains. Measurements are made at 300 K and 10 MHz at the Al" nuclear position in AlSb, at Ga in GaP, and at In'" in InP. Improved measurements are also made at the Ga ' nuclear position in GaAs and GaSb, at In'" in InAs and InSb, at As" in InAs and GaAs, at Sb in AlSb, GaSb, and InSb. Theoretical S» and S4, are computed assuming them to be sums of ionic and covalent contributions. Ionic contributions are approximated by point charges of the four first neighbors with efFective charge Z». Covalent contributions are computed using atomic wave functions and bond polarity values a . Z» and a are taken from Harrison's bond-optical model (BOM). Comparisons of theoretical and experimental S» give (i) the sign of Z» at the group-V atom as negative, (ii) agreement with the ratio of BOM values of Z* in seven compounds, and (iii) signs and magnitudes of ionic and covalent contributions.

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