Synthesis, structure and physical properties of YbNi3Al9.23.

The physical properties of YbNi(3)Al(9.23(1)), including the crystal structure, magnetization, specific heat, valence, and electrical resistivity, are reported. Single crystal x-ray diffraction reveals that the compound crystallizes with the rhombohedral space group R32 and has unit cell parameters a = 7.2443(3) Å and c = 27.251(3) Å with some crystallographic disorder at Al sites. The compound orders antiferromagnetically at T(N) = 3 K despite the presence of strong ferromagnetic correlations, accompanied by a spin-flop-like transition to a moment-aligned state above 0.1 T. X-ray absorption spectroscopy and magnetic susceptibility measurements indicate a localized Yb(3+) electronic configuration, while the Sommerfeld coefficient for the magnetically ordered state was determined as approximately 135 mJ mol(-1) K(-2), suggesting moderately heavy fermion behavior. Therefore, these data indicate a balance between competing Ruderman-Kittel-Kasuya-Yosida (RKKY) and Kondo interactions in YbNi(3)Al(9.23(1)) with a somewhat dominant RKKY interaction that leads to a relatively high ordering temperature.