Properties of strongly diamagnetic YbZn2Sb2

R. Vollmer1, C. Pfleiderer1, M. Uhlarz1, H. v. Löhneysen1,2 und A. Nateprov3
2Forschungszentrum Karlsruhe, Institut für Festkörperphysik
3Institute of Applied Physics, Academer 5, MD-2028 Kishniev, Moldova
1Physikalisches Institut, Universität Karlsruhe

The f13 electronic configuration of elementary Yb suggests formally an electron-hole analogy of Yb-based intermetallic compounds with Ce-based materials. Contrary to Ce-based materials the application of pressure is expected to drive intermediate-valent Yb-based compounds towards antiferromagnetic ordering. In semi-metallic YbZn2As2 antiferromagnetic order was previously reported at TN = 0.4 K below a strong high temperature Curie-Weiss susceptibility (meff = 2.35mB). Single-crystal samples of YbZn2Sb2 have been prepared by sintering high-purity starting materials in a carbon-glass crucible at 1200° C. The structure was determined by Cu Ka powder diffraction and found to be the same as for YbZn2As2 (P3m1) with a lattice constant increased by 6.3%. Resistivity, magnetisation and specific heat have been measured at low T and high magnetic field to characterise the properties of YbZn2Sb2. In contrast to expectation YbZn2Sb2 is, however, not intermediate valent, but is a strongly diamagnetic semi-metal, where the diamagnetism exceeds Larmor elemental contributions by more than three orders of magnitude.