Key points are not available for this paper at this time.
The anomalous Hall effect in two-dimensional ferromagnets is discussed to be the physical realization of the parity anomaly in (2+1)D, and the band crossing points behave as the topological singularity in the Brillouin zone. This appears as the sharp peaks and the sign changes of the transverse conductance σxy as a function of the Fermi energy and/or the magnetization. The relevance to the experiments including the three dimensional systems is also discussed.
Onoda et al. (Tue,) studied this question.