  One of the most appealing features of magnonics is the easy tunability of
spin-waves propagation via external magnetic fields. Usually this requires
bulky and power-hungry electromagnets which are not compatible with device
miniaturization. Here we propose a different approach, exploiting the stray
field from permanent micromagnets integrated on the same chip of a magnonic
wave-guide. In our monolithic device, we employ two SmCo square micromagnets
(10x10 $\mu$m$^2$) flanking a CoFeB conduit at different distances from its
axis, to produce a tunable transverse bias field between 7.5 and 3.0 mT in the
conduit region between the magnets. Spin waves excited by an antenna just
outside the region between the magnets enter a region with a variable higher
(lower) effective field when an external bias field is applied parallel
(antiparallel) to that from the micromagnets. Consequently, the attenuation
length and phase shift of Damon-Eshbach spin waves can be tuned in a wide range
by playing with the parallel-antiparallel configuration of the external bias
and the distance between SmCo micromagnets and the CoFeB conduit. This work
demonstrates the potential of permanent micro-magnets for the realization of
low-power, integrated magnonic devices with tunable functionalities.
