Transport and magnetic properties of new heavy-fermion antiferromagnet YbNi3Al9

We have synthesized a new Yb-based Kondo-lattice compound YbNi3Al9. This compound crystallizes in a trigonal ErNi3Al9-type structure (space group R32), in which the Yb-ion is arranged in a two-dimensional honey-comb lattice perpendicular to the c-axis. We report the first measurements of electrical resistivity and magnetization for single-crystalline samples of YbNi3Al9. The electrical resistivity of YbNi3Al9 is characteristic of the typical properties of heavy-fermion antiferromagnets with a Neel temperature of TN = 3.4 K. The transport and magnetic properties exhibit large anisotropy in the low-temperature region owing to an interplay among the crystalline-electric-field effect, the Ruderman-Kittel-Kasuya-Yoshida interaction, and the Kondo effect. Below TN, the metamagnetic transition is observed at a very low magnetic field of around 1 kOe with the field applied along the a-axis. The magnetic structure of YbNi3Al9 is highly sensitive to the applied magnetic field.