  Magnetic nanowires (NW) are promising candidates for heat generation under
AC-field application due to their large shape anisotropy. They may be used for
catalysis, hyperthermia or water purification treatments. In the present work
we theoretically evaluate the heat dissipated by a single magnetic nanowire,
originated from the domain wall dynamics under the action of an AC-field. We
compare the Permalloy NWs (which demagnetize via the transverse wall
propagation) with the Co fcc NWs whose reversal mode is via a vortex domain
wall. The average hysteresis loop areas -which are proportional to the Specific
Absorption Rate (SAR)- as a function of the field frequency have a pronounced
maximum in the range 200MHz-1GHz. This maximum frequency is smaller in
Permalloy than in Co and depends on the nanowire length. A simple model related
to the nucleation and propagation time and domain wall velocity (higher for the
vortex than for the transverse domain wall) is proposed to explain the
non-monotonic SAR dependence on the frequency.
