  The finite-temperature magnetism of a monolayer on a bcc (110) surface was
examined using a model Hamiltonian containing ferromagnetic or
antiferromagnetic exchange interactions, Dzyaloshinsky-Moriya interactions and
easy-axis on-site anisotropy. We examined the competition between the collinear
ground state parallel to the easy axis and the spin spiral state in the plane
perpendicular to this axis preferred by the Dzyaloshinsky-Moriya interaction.
Using approximative methods to calculate the magnon spectrum at finite
temperatures, it was found that even if the ground state is collinear,
increasing the Dzyaloshinsky-Moriya interaction strongly decreases the critical
temperature where this collinear order disappears. Using atomistic spin
dynamics simulations it was found that at this critical temperature the system
transforms into the non-collinear state. Including external magnetic field
helps stabilising the ferromagnetic state. An effect due to the finite size of
the magnetic monolayer was included in the model by considering a different
value for the anisotropy at the edges of the monolayer. This effect was shown
to stabilize the spin spiral state by fixing the phase at the ends of the
stripe.

Strongly Correlated Electrons;Mesoscale and Nanoscale Physics