ANISOTROPIC MAGNETORESISTANCE OF THE SEMIMETALLIC ANTIFERROMAGNET EUAS3

The Hall effect and the magnetoresistance of single crystals of EuAS3 have been measured in the temperature region of magnetic ordering. We observe an extreme anisotropic behavior. When the magnetic field is applied perpendicular to the buckled As layers of the EuAS3 crystal structure, a strong positive magnetoresistance is found, similar to the case of alpha-As. The situation changes completely with the magnetic field parallel to [010], the direction of the ordered Eu2+ moments in the low-temperature AF1 phase of EuAs3. In this case, the magnetoresistance is much weaker and reflects the field-induced magnetic phase transitions, similar to the case of the rare-earth metals Dy and Ho. We discuss these features on the basis of superzone and spin-fluctuation scattering.