  We use a recently developed bosonic mean-field theory (MFT) to study the
ordered ground states of frustrated Heisenberg antiferromagnets (FHAFM) in two
dimensions. We emphasize the role of condensates in satisfying the MF
variational equations and their relation to spin correlation functions at low
temperatures. Our results are similar to those obtained using Schwinger boson
MFT. However, we emphasize here that our MFT has three bosons at each site and
that it is not necessary to rotate the quantization axes on appropriate
sub-lattices to align all the spins ferromagnetically. This MFT is also closely
related to a new spin-wave theory which enables us to obtain the spin-wave
spectrum easily (without any rotation of axes) for an entire class of
three-dimensionally ordered states. For the FHAFM on a triangular lattice, we
use this theory to compute the spin-wave spectrum for all values of $~J_2 ~/J_1
~$ and demonstrate the phenomenon of order from disorder. (1 figure not
included. Hard copy available on request.)
