  Near the Curie temperature of a ferromagnet the form of a domain wall changes
from the Bloch type to (asymptotically) the linear Zhirnov wall. Unlike the
simple 180 degree rotation of the magnetization vector in a Bloch wall, its
absolute value diminishes near the center of the wall. This leads to a decrease
of the total transverse component of the exchange field inside the wall and to
an increase of mistracking of the spins of the electrons traversing the wall.
This mechanism may help explain large magnetoresistance of domain walls in thin
nanowires, as the Curie temperatures of low-dimensional nanostructures are
known to be lower than in bulk ferromagnets while the anisotropy energy stays
virtually unchanged.
