  We investigate the spectral and localization properties of unmagnetized
Heisenberg-Mattis spin glasses, in space dimensionalities $d=2$ and 3, at T=0.
We use numerical transfer-matrix methods combined with finite-size scaling to
calculate Lyapunov exponents, and eigenvalue-counting theorems, coupled with
Gaussian elimination algorithms, to evaluate densities of states. In $d=2$ we
find that all states are localized, with the localization length diverging as
$\omega^{-1}$, as energy $\omega \to 0$. Logarithmic corrections to density of
states behave in accordance with theoretical predictions. In $d=3$ the
density-of-states dependence on energy is the same as for spin waves in pure
antiferromagnets, again in agreement with theoretical predictions, though the
corresponding amplitudes differ.
