  The stability of antiferromagnetic long-range order against quenched disorder
is considered. A simple model of an antiferromagnet with a spatially varying
Neel temperature is shown to possess a nontrivial fixed point corresponding to
long-range order that is stable unless either the order parameter or the
spatial dimensionality exceeds a critical value. The instability of this fixed
point corresponds to the system entering a random-singlet phase. The
stabilization of long-range order is due to quantum fluctuations, whose role in
determining the phase diagram is discussed.
