  The control of topological quantum materials is the prerequisite for novel
devices exploiting these materials. Here we propose that the room temperature
ferromagnet Fe3Sn2, whose fundamental building blocks are Kagome bilayers of
iron, hosts Weyl nodes at the Fermi level which can move in momentum space
depending on the direction of the magnetization, itself readily controlled
either by modest external fields or temperature. The proposal is derived from
density functional calculations, including a mean field treatment of Hubbard
repulsion U, which have been validated by comparison with angle-resolved
photoemission data. Ferromagnetism with magnetization along certain directions
is shown to lift the Weyl degeneracies, while at the same time inducing texture
in the quasiparticle spin polarizations mapped in reciprocal space. In
particular, the polarization is attenuated and then rotated from parallel to
perpendicular to antiparallel to the magnetization as Weyl points derived from
crossing of majority and minority spin bands are traversed.
