Thomas, Michaels, ETH Zurich #
Thermal fluctuations and domain walls in ultra-thin magnetic nanowires #
The possibility of inducing domain-wall (DW) motion in magnetic
nanowires by means of spin polarised electric currents has recently renewed 
theoretical interest in this field. The problem is usually modelled
on a micro-magnetic approach, but ignoring any thermal fluctuations.
However, some relevant experimental facts - like the correct order of magnitude of the critical current needed for DW motion - still lack 
satisfactory
explanations. We thus developed a general theoretical framework, which
highlights the crucial role played by thermal fluctuations at the centre 
of
DWs. The latter qualitatively and quantitatively accounts for a variety
of problems relating to DWs at finite temperatures. Examples are the
shrinking of magnetic domains observed in Fe ultra-thin 
films on Cu(001)
substrates with increasing temperature, the inverse symmetry breaking in
ultra-thin films
 and the renormalisation of the critical current for 
domain-
wall motion at finite
 temperatures.