The temperature variation of the resistivity rho and specific heat C have been measured for prototypical half-metallic ferromagnets, R0. 6Sr 0.4MnO3, by controlling the one-electron bandwidth W. We have found variations in the temperature scalings of rho from approximately T2 ( R = La, and Nd) to approximately T3 ( R = Sm), and have interpreted the T3 law in terms of the anomalous single-magnon scattering process in the half-metallic system.