MAGNETIC-SUSCEPTIBILITY AND MAGNETIZATION MEASUREMENTS OF AN YBAL3 SINGLE-CRYSTAL FOR GROUND-STATE INVESTIGATIONS

The intermetallic compound YbAl3 (cubic AuCu3 structure type) has been usually classified as an intermediate valence system. As many rare earth intermetallics it might be in general described by the Anderson model for the f-electron hybridization with the conduction electrons. To understand in detail the electron hybridization, the magnetization of a flux-grown YbAl3 single crystal was investigated with a SQUID-magnetometer at different temperatures in applied fief ds up to B=5T. Measurements along the crystallographic axes [100] and [110] show no anisotropy. We used the same single crystal for determining the magnetic susceptibility in the temperature range between T=2 K and T=300 K. We have observed the well-known maximum at T=130 K in agreement with earlier measurements on polycrystals. This maximum as well as a Curie-Weiss-temperature dependence at higher temperatures are typical features of many Ce- and Yb-compounds. For T<6 K the magnetic susceptibility increases rapidly when temperature is decreased. This increase might be explained with a magnetic impurity contamination of less than 100 ppm. Due to this high purity of the sample we could directly measure a small maximum of (chi)(T) at T=15 K, that was earlier only separated by subtracting the larger impurity contribution. This maximum has to be taken into account when describing the hybridization process in detail.