Crystal Growth, Transport, and the Structural and Magnetic Properties of Ln4FeGa12 with Ln = Y, Tb, Dy, Ho, and Er

摘要

Ln4FeGa12, where Ln is Y, Tb, Dy, Ho, and Er, prepared by flux growth, crystallize with the cubic Y4PdGa12 structure with the Im3hm space group and with a = 8.5650(4), 8.5610(4), 8.5350(3), 8.5080(3), and 8.4760(3)A°, respectively.The crystal structure consists of an iron-gallium octahedra and face-sharing rare-earth cuboctahedra of the Au3Cu type. Er4Fe0.67Ga12 is iron-deficient, leading to a distortion of the octahedral and cuboctahedral environments due to the splitting of the Ga2 site into Ga2 and Ga3 sites. Further, interstitial octahedral sites that are unoccupied in Ln4FeGa12 (Ln = Y, Tb, Dy, and Ho) are partially occupied by Fe2. Y4FeGa12 exhibits weak itinerant ferromagnetism below 36 K. In contrast, Tb4FeGa12, Dy4FeGa12, Ho4FeGa12, and Er4Fe0.67Ga12 order antiferromagnetically with maxima in the molar magnetic susceptibilities at 26, 18.5, 9, and 6 K. All of the compounds exhibit metallic electric resistivity, and their iron-57M ossbauer spectra, obtained between 4.2 and 295 K, exhibit a single-line absorption with a 4.2 K isomer shift of ca. 0.50 mm/s, a shift that is characteristic of iron in an iron-gallium intermetallic compound. A small but significant broadening in the spectral absorption line width is observed for Y4FeGa12 below 40 K and results from the small hyperfine field arising from its spin-polarized itinerant electrons.