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.