title: Magnetic order in Pu₂M₃Si₅ (M = Co, Ni).
abstract: The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of two new plutonium compounds Pu2M3Si5 (M = Co, Ni) are reported. Pu2Ni3Si5 crystallizes in the orthorhombic U2Co3Si5 structure type, which can be considered a variant of the BaAl4 tetragonal structure, while Pu2Co3Si5 adopts the closely related monoclinic Lu2Co3Si5 type. Magnetic order is observed in both compounds, with Pu2Ni3Si5 ordering ferromagnetically at T(C) = 65 K then undergoing a transition into an antiferromagnetic state below T(N) = 35 K. Two successive magnetic transitions are also observed at T(mag1) = 38 K and T(mag2) = 5 K in Pu2Co3Si5. Specific heat measurements reveal that these two materials have a moderately enhanced Sommerfeld coefficient γ ∼ 100 mJ/mol Pu K(2) in the magnetic state with comparable RKKY and Kondo energy scales.
authors.affiliation: Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: E D
authors.initials: ED
authors.lastname: Bauer
authors.forename: P H
authors.initials: PH
authors.lastname: Tobash
authors.forename: J N
authors.initials: JN
authors.lastname: Mitchell
authors.forename: J A
authors.initials: JA
authors.lastname: Kennison
authors.forename: F
authors.initials: F
authors.lastname: Ronning
authors.forename: B L
authors.initials: BL
authors.lastname: Scott
authors.forename: J D
authors.initials: JD
authors.lastname: Thompson