  We have observed peculiar magnetization textures in Ni$_{80}$Pd$_{20}$
nanostructures using three different imaging techniques: magnetic force
microscopy, photoemission electron microscopy under polarized X-ray absorption,
and scanning electron microscopy with polarization analysis. The appearances of
diamond-like domains with strong lateral charges and of weak stripe structures
bring into evidence the presence of both a transverse and a perpendicular
anisotropy in these nanostrips. This anisotropy is seen to reinforce as
temperature decreases, as testified by a simplified domain structure at 150 K.
A thermal stress relaxation model is proposed to account for these
observations. Elastic calculations coupled to micromagnetic simulations support
qualitatively this model.
