  Motivated by recent discovery of canted ferromagnetism in Tsai-type
approximants Au-Si-RE (RE = Tb, Dy, Ho), we propose a phenomenological magnetic
model reproducing their magnetic structure and thermodynamic quantities. In the
model, cubic symmetry ($m\bar{3}$) of the approximately-regular icosahedra
plays a key role in the peculiar magnetic structure determined by a neutron
diffraction experiment. Our magnetic model does not only explain magnetic
behaviors in the quasicrystal approximants, but also provides a good starting
point for the possibility of coexistence between magnetic long-range order and
aperiodicity in quasicrystals.
