  A simple analytical method for study the magnetic properties of the
finite-length biatomic chains in the framework of Heisenberg model with
uniaxial magnetic anisotropy is proposed. The method allows to estimate the
reversal time of the magnetization of ferromagnetic and antiferromagnetic
biatomic chains. Three cases are considered: the spontaneous remagnetization,
the remagnetization under the interaction with a scanning tunneling microscope,
and the remagnetization in the external magnetic field. The applicability
limits of the method are discussed. Within its limits of applicability the
method gives results which are in perfect agreement with the results of the
kinetic Monte Carlo simulations. As the examples, two physical systems are
considered: biatomic Fe chains on Cu2N/Cu(001) surface and biatomic Co chains
on Pt(997) surface. The presented method is incomparably less time-consuming
than the standard kMC simulations, especially in the cases of low temperatures
or long chains.
