“…Interactions such as biquadratic coupling, three-site four-spin interaction, and four-site four-spin interaction have been discussed by many investigators. In particular, the practical interest in biquadratic interaction started when it had to be added to the usual bilinear Heisenberg exchange to explain some magnetic properties of materials, such as MnAs, TbSb, MnO, α-MnS, EuSe, rare-earth vanadates, arsenates, and phosphates [7]. Furthermore, it was shown that in some materials a biquadratic-like interaction is dominant (see, e.g., [8]).…”