An unusual hollow cylindrical Fermi surface of a quasi-two-dimensional compound CeAgSb₂

Abstract

We have carried out the de Haas-van Alphen (dHvA) experiment, together with electrical resistivity, magnetic susceptibility, magnetization and specific heat experiments on a high-quality single-crystal CeAgSb₂, which has a small net ferromagnetic moment of 0.4 μ_B per Ce atom. The bulk magnetic properties are well explained by the crystalline electric field scheme. On the other hand, large dHvA frequencies of 10⁸ Oe, which correspond to cylindrical Fermi surfaces, were detected by the dHvA measurement for the magnetic field along the tetragonal [001] direction, indicating the quasi-two-dimensional electronic structure. The dHvA branches of CeAgSb₂ are highly different from those with small dHvA frequencies of 10⁷ Oe for the reference compounds LaAgSb₂ and YAgSb₂ which exhibit a semimetallic character. The dHvA results have been compared with the results of the energy band calculations. It was concluded that the 4f electron is mainly localized and that the Fermi surface of CeAgSb₂ is similar to that of LaAgSb₂, but it is slightly enlarged so as to form the large orbits along a hollow cylindrical Fermi surface.