15 new superconducting and magnetic noncentrosymmetric cage compounds
Crystallographically complex compounds often possess peculiar physical properties, the evolution of which can be tracked by changing one of the constituent elements at a time. We report the discovery and synthesis of isotypic R4Be33Pt16 (R = Y, La–Nd, Sm–Lu) compounds, which crystallize with the noncentrosymmetric cubic space group I-43d. The lattice parameters vary from a = 13.6682(4) Å for R = La to a = 13.4366(3) Å for R = Lu. R4Be33Pt16 phases exhibit a wide range of ground states. R = Y, La, and Lu analogs display superconductivity. Their calculated electronic structures show nonzero density of states at the Fermi level, with the value of the Sommerfeld coefficient consistent with those obtained experimentally. The rest of the R4Be33Pt16 compounds exhibit magnetic ground states with ordering temperatures ranging from Tmag = 0.4 K (R = Yb) to Tmag = 40 K (R = Pr). The diversity of physical properties of R4Be33Pt16 compounds can likely be attributed to the nature of the individual rare-earth elements, structural noncentrosymmetry, the large number of atoms per unit cell (212), as well as the complex multicenter interactions within the Be-Pt framework.