Properties of strongly diamagnetic YbZn2Sb2

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

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.