High Quality Single-Crystal Growth and De Haas–Van Alphen Measurements of YbAl2

Abstract

To clarify the electronic structure of Yb-based compounds, further investigation of typical heavy-fermion system and intermediate valence system are required. In this work, we focus on YbAl2, which is known an intermediate valence compound with Yb-valence of +2.25. We have succeeded in measuring the de Haas-van Alphen effect of YbAl2 using the high-quality single-crystalline sample synthesized by the new crystal-growth method named “wrap method”. The Fermi surface topology of YbAl2 is distinctly different from that of iso-structural trivalent compound LaAl2. The cyclotron effective masses are in the range of 0.8m0 to 2.0m0. These results clearly confirm that in the intermediate valence state of YbAl2, the Yb-valence is close to divalent rather than trivalent.