Magnetic-field effects on the pseudogap in CeRhAs

The electrical resistivity and magnetization M(H) of single crystal CeRhAs, which is the so-called Kondo insulator, have been measured in magnetic field up to 55 T. At 1.3 K, the slopes of M(H\\b) and M(H\\c) decrease at around 16 and 13 T, respectively, while M(H\\a) increases monotonously. The longitudinal magnetoresistances along the b- and c-axes show characteristic structures partly associated with the anomaly of M(H), while it along the a-axis shows only a broad maximum. The transverse magnetoresistances for I\\b follow H-gamma (gamma = 1.5 similar to 1.7). These observations suggest the existence of a narrow and anisotropic structure within the wide pseudogap. (C) 2003 Elsevier Science B.V. All rights reserved.