Magnetic ordering in Kondo lattice compound YbIr₃Si₇

We discovered a new ytterbium intermetallic compound YbIr₃Si₇ (space group: R3-bar c, no.167). The single crystal was obtained via the flux method. We measure the electric resistivity, specific heat, and magnetization of this material. YbIr₃Si₇ is a Kondo lattice compound having a high magnetic order temperature of 18 K, and it exhibits double magnetic transitions at 4 and 18 K. We evaluate the magnetic order temperature of 18 K using the Arrott plot measured in the magnetic field along the c-axis. The spontaneous moment of this material is 0.35 μ_B, and this value is much smaller than that of a free Yb³⁺ ion of 4.54 μ_B. Canted-antiferromagnetic stacking along the c-axis may be realized below 18 K, where magnetic moments ferromagnetically align on a Yb triangular lattice in the c-plane. (author)