The binary system Pu–Si: crystallochemistry and magnetic properties

Abstract

The crystallochemistry of the plutonium-silicon binary system is being investigated. We report on the observation of five binary phases: PuSi 2 (ThSi 2 and AlB 2 type), PuSi (FeB type), Pu 3 Si 2 (U 3 Si 2 type) and Pu 5 Si 3 (W 5 Si 3 type). Preliminary characterizations of the electronic properties of PuSi 2 (ThSi 2 type) and PuSi (FeB type) were undertaken by SQUID magnetometry and electrical resistivity measurements. PuSi 2 does not order magnetically down to 2 K, whereas PuSi undergoes a ferromagnetic transition at T C ∼ 72 K.

Magnetic state and electronic structure of theδandαphases of metallic Pu and its compounds

“…Structural and magnetic properties of PuSi 2 were reported by Boulet et al 100 although this phase was earlier investigated in Ref. 101.…”

“…100 PuSi 2 susceptibility curve shows Curie-Weiss behavior 100,102 with p ef f = 0.54 µ B , Θ p = -58 K, and χ 0 = 2.3 × 10 −5 emu mol −1 (Ref. 100). Almost field independent resistivity shows a broad maximum at 18 K suggesting strong spin fluctuations.…”

“…This compound crystallizes in tetragonal T hSi 2 -type (space group I4 1 /amd) structure with a = 3.9707(3)Å and c = 13.6809(5)Å. 100 PuSi 2 susceptibility curve shows Curie-Weiss behavior 100,102 with p ef f = 0.54 µ B , Θ p = -58 K, and χ 0 = 2.3 × 10 −5 emu mol −1 (Ref. 100).…”

“…Almost field independent resistivity shows a broad maximum at 18 K suggesting strong spin fluctuations. 100 The LDA band structure ( Fig. 9(a)) shows a broad deep pseudogap with a very small density of states value on the Fermi level.…”

Magnetic properties of ferromagnetic Pu2Pt3Si5

“…The magnetic order and its type are only well established in a few cases, and among them, a very small fraction is ferromagnetic (Table 3). At first glance it appears that ferromagnetism is mainly observed in the Pu binaries [41][42][43][44][45][46][47][48][49]. One reason for this is a clear lack of knowledge of basic properties at low temperature of Pu-based ternaries [29,50].…”