  Nearest-neighbor spin correlations are considered near the surface of a
semi-infinite spin-$\frac12$ Heisenberg antiferromagnet on a simple cubic
lattice. In the spin-wave approximation, the excitation spectrum of this model
involves bulk modes -- standing spin waves and a quasi-two-dimensional mode of
surface spin waves. These latter excitations eject the bulk excitations from
the surface region thus dividing the antiferromagnet into two parts with
different excitations. As a result absolute values of the spin correlations
near the surface exceed the bulk value. In the surface region, the pattern of
spin correlations resembles the comb structure recently obtained for the
two-dimensional case.
