High-pressure high-temperature synthesis of non-centrosymmetric R3Pt4Ge13 compounds with R = Gd, Dy, Ho, Er and Lu

Abstract

New compounds of composition R3Pt4Ge13 have been successfully prepared with R = Dy, Ho, Er and Lu, by high-pressure (5–7 GPa) and high-temperature synthesis (up to 1073 K). Structural analysis confirms that all compounds crystallize in a non-centrosymmetric monoclinic structure (space group Cc). The magnetic properties of these four new compounds were studied, as well as those of Gd3Pt4Ge13, a known compound on which few physical studies have been published. The magnetic susceptibility of the Gd, Dy, Ho and Er compounds follow a Curie-Weiss law in the temperature range 20 K–300 K, consistent with a trivalent state of the R ions. At lower temperature, magnetization and heat capacity measurements reveal antiferromagnetic ordering in Gd3Pt4Ge13 (TN = 6.2 ± 0.1 K) and a ferromagnetic one in Er3Pt4Ge13 (TC = 2.2 ± 0.1 K). Dy3Pt4Ge13 presents a magnetic order at T∗ = 1.8 ± 0.2 K. Ho3Pt4Ge13 behaves as a Van Vleck type paramagnet below 10 K and Lu3Pt4Ge13 is found to be diamagnetic between 2 K and 300 K. This last compound shows no superconducting transition down to 400 mK.