HIGH-PRESSURE MOSSBAUER STUDIES ON YB HEAVY-FERMION COMPOUNDS

The discovery that some Yb intermetallic compounds exhibit many of the interesting Kondo-related properties found in analogous Ce compounds has led to a number of new experimental and theoretical activities to understand the ground state properties of this class of materials. In this paper we give a brief review of our very recent results on the ef fect of pressure on the magnetic and electronic properties of the ferr omagnetic Kondo lattice (KL) YbNiSn and isostructural antiferromagneti c KL YbPtAl using the Yb-170 Mossbauer effect technique, electrical re sistance and X-ray diffraction, respectively. We show that the magneti c ground state properties of YbNiSn and YbPtAl are governed by a volum e dependent competition between frustrated anisotropic exchange intera ctions and the crystal electric field anisotropy rather than by a dire ct competition between Kondo and RKKY interactions.