  We consider classical spin models of two- and three-dimensional spins with
continuous symmetry and investigate the effect of a symmetry-breaking
unidirectional quenched disorder on the magnetization of the system. We work in
the mean-field regime. We show, by perturbative calculations and numerical
simulations, that although the continuous symmetry of the magnetization is lost
due to disorder, the system still magnetizes in specific directions, albeit
with a lower value as compared to the case without disorder. The critical
temperature, at which the system starts magnetizing, as well as the
magnetization at low and high temperature limits, in presence of disorder, are
estimated. Moreover, we treat the SO(n) n-component spin model to obtain the
generalized expressions for the near-critical scalings, which suggest that the
effect of disorder in magnetization increases with increasing dimension. We
also study the behavior of magnetization of the classical XY spin model in the
presence of a constant magnetic field, in addition to the quenched disorder. We
find that in presence of the uniform magnetic field, disorder may enhance the
component of magnetization in the direction that is transverse to the disorder
field.
