  Conductive ferroelectric domain walls (DWs) represent a promising topical
system for the development of nanoelectronic components and devices. DWs show
very different properties as compared to their bulk counterparts. Of central
interest here is the domain wall current (DWC) of charged DWs in 5mol\%
Mg-doped lithium niobate single crystals; in contrast to former works, we
extend the DWC study here to temperatures as high as 400$^\circ$C. Both the
temporal stability and the thermal activation energies of 90 - 160 meV are
readily deduced from current-voltage sweeps as recorded over multiple heating
cycles. Our experimental work is backed up by atomistic modelling of the DWC.
The latter suggests that a large band bending renders head-to-head and
tail-to-tail DWs semimetallic. These detailed investigations underline the
potential to extend DWC-based nanoelectronic applications even into the so-far
unexplored high-temperature regime.
