# On the anomalous Hall effect

ubergewehr273
Hi!

Reading through this paper, the Hall resistivity in ferromagnetic materials is given by $$\rho_H = R_0 B + 4 \pi R_s M$$

It is mentioned that ##R_s## (anomalous Hall coefficient) is significantly larger than ##R_0## (ordinary Hall coefficient) and has a strong dependence on temperature. However, I'm unable to understand why this is the case. Temperature dependence is taken care of by the magnetization ##M## of the material i.e. decreases as the temperature increases. So why does ##R_s## have to be temperature dependent? All the texts that I've referrred seem to suggest that this is just experimental observation, which I'm not really satisfied with.

Also, why does ##R_s \gg R_0## have to hold true? I'd really appreciate if someone could explain this to me.