Anomalous pressure-temperature-dependent Hall constants in CeP and Yb₄As₃

The Hall coefficient of CeP is found to change in sign from negative to positive with increasing pressure. This result clearly indicates the fact that there exists a successive electronic transition from a dense Kondo to a normal metal through a mixed-valence state. For Yb₄As₃, the huge peak in the temperature-dependent Hall coefficient is found to decrease with increasing pressure. This result indicates that the anomalous temperature-dependent resistivity is primarily caused by the carrier concentration depending strongly on temperature.