R. Vollmer¹, C. Pfleiderer¹, M. Uhlarz¹, H. v. Löhneysen^1,2 und A. Nateprov^3
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 T_N = 0.4 K below a strong high temperature Curie-Weiss susceptibility (m_eff = 2.35m_B). 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 K_a 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.