Physical properties of the R3Pt23Si11 compounds with volatile rare earth: Sm, Eu, Tm and Yb

Christine Opagiste (1) , Camille Barbier (1) , Richard Haettel (2) , Rose-Marie Galéra (1)

1 NEEL - MagSup - Magnétisme et Supraconductivité
2 NEEL - ExpE - Ingénierie Expérimentale

The new R3Pt23Si11 series, where R is a rare earth, has been completed with the synthesis of three new compounds with volatile rare earth : R = Eu, Sm, and Tm. The studies of their physical properties have been performed along with those of the Yb3Pt23Si11 compound. The X-ray powder diffrac-tion patterns confirm that they all crystallize in the same face-centered cubic structure, space group F m - 3m, as the rest of the series. The refinements of the diffraction patterns show an anomalously high lattice parameter in Eu3Pt23Si11 and Yb3Pt23Si11, indicating a divalent valence state for Eu and Yb. This 2+ valence state for Eu and Yb ions is confirmed by the magnetic measurements. A ferromagnetic order is observed at Tc = 5.54±0.07 K and 10.12±0.07 K in Eu3Pt23Si11 and Sm3Pt23Si11 respectively. In Tm3Pt23Si11 no magnetic order is found down to 0.36 K while Yb3Pt23Si11 reveals a dia-magnetic behavior. At low temperatures the spontaneous moment, Ms , in Eu3Pt23Si11 is in agreement with a L=0, S=7/2 state for the Eu 2+ ion. On the contrary in Sm3Pt23Si11, Ms is far below the 0.714 µB expected for the saturated moment of the Sm 3+ in the J =7/2 ground state multiplet.

Mots clés: Rare-earth intermetallics; Ferromagnetism; Van Vleck paramagnetism; Diamagnetism

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Christine Opagiste, Camille Barbier, Richard Haettel, Rose-Marie Galéra. Physical properties of the R3Pt23Si11 compounds with volatile rare earth: Sm, Eu, Tm and Yb. Journal of Magnetism and Magnetic Materials, 2015, Journal of Magnetism and Magnetic Materials, 378, pp.402-408. ⟨10.1016/j.jmmm.2014.11.070⟩. ⟨hal-01090632⟩