  Within the frameworks of the model using ab initio calculation data on d-band
filling and on the shape of density of d-electron states in Fe2-xMnxAs, the
mechanisms of stabilization of non-collinear magnetic ordered phases observed
within the range of 1.19 <= x <= 1.365 are considered. The relation between
baric peculiarities of the changes in stability of noncollinear phases and
changes in the electronic structure characteristics of Fe2-xMnxAs due to
lattice deformation is disclosed. It is found that stabilization of
non-collinear phases and change in type of order-order phase transition with
decreasing manganese is determined by competition between the electronic
filling of the d-band, shape of the d-electron density of states and structural
features of these phases.
