  Boundary conditions for order parameters at an interface between
ferromagnetic (FM) and two-sublattice antiferromagnetic (AFM) materials were
obtained in the continuous medium approximation similarly to the approach which
allows one to take into account the finite thickness of the FM/FM interface,
which is much less than spin wave length. Three order parameters are considered
inside an interface of finite thickness with the magnetization
$\mathbf{\text{M}}$ of FM, magnetizations of both sublattices
$\mathbf{\text{M}}_{1}$ and $\mathbf{\text{M}}_{2}$ of AFM. The uniform and
non-uniform exchange between all order parameters are taken into account to the
interface energy. Using these boundary conditions, the excitation of a surface
evanescent spin wave is considered in AFM when the spin wave in FM falls onto
this interface. The coefficients and the phases of transmission and reflection
of spin wave through the FM/AFM interface are derived.
