  The creation of temperature variations in magnetization, and hence in the
frequencies of the magnon spectrum in laser-heated regions of magnetic films,
is an important method for studying Bose-Einstein condensation of magnons,
magnon supercurrents, Bogoliubov waves, and similar phenomena. In our study, we
demonstrate analytically, numerically, and experimentally that, in addition to
the magnetization variations, it is necessary to consider the connected
variations of the demagnetizing field. In case of a heat induced local minimum
of the saturation magnetization, the combination of these two effects results
in a local increase in the minimum frequency value of the magnon dispersion at
which the Bose-Einstein condensate emerges. As a result, a magnon supercurrent
directed away from the hot region is formed.
