Rare‐Earth Cobalt Gallides RE₄Co₃Ga₁₆ (RE = Gd–Er, Y): Self‐Interstitial Derivatives of RE₂CoGa₈

Abstract

Keywords: Rare earths / Cobalt / Gallium / Intermetallic phases / Magnetic properties Ternary rare-earth cobalt gallides RE 4 Co 3 Ga 16 (RE = Gd-Er, Y) have been prepared by arc-melting of the elements followed by annealing at 800°C. Single crystals of the Gd and Tb members were also grown in the presence of a Ga selfflux. They extend the rare-earth substitution possible in the Sm 4 Co 3 Ga 16 -type structure (Pearson symbol tP23, space group P4/mmm, Z = 1), in which additional Co atoms enter as self-interstitials into the parent RE 2 CoGa 8 structure. Structural refinements were carried out on single-crystal (RE = Gd, Tb) and powder (RE = Dy, Ho, Er, Y) X-ray diffraction data. Cell parameters lie in the ranges of a = 6.03-5.96 Å and c =

Single crystal growth and anisotropic physical properties of Sm4Co3Ga16

“…The corresponding effective moment from the Curie-Weiss fitting is 0.66 µ B /Sm with Weiss temperature of −8.5 K for H ab, while it is 0.81 µ B /Sm with Weiss temperature −49.2 K for H c. The polycrystalline average of these anisotropic effective moments gives 0.71 µ B /Sm, which is similar to the previous report (0.68 µ B /Sm) [28] and slightly smaller than the expected value of 0.85 µ B for free Sm 3+ ion. Although it has been attributed to intermediate valence state of Sm ion in the previous reports [11,28], Sm ion appears to be well localized in this system based on the our study, which will be discussed further in the following sections. As alternative possibilities, the reduced moment can be originated from crystal field effect and/or possible weak deficiency in Sm-site.…”

“…Interestingly, recent article on Sm 4 Co 3 Ga 16 , which has similar crystal structure with that of Sm 2 CoGa 8 , presented superconducting transport and magnetic properties in this compound [11]. In Sm 4 Co 3 Ga 16 , additional Co atoms enter as self-interstitials into the parent Sm 2 CoGa 8 structure while keeping the same crystallographic space group [28]. Slightly lowered effective moment of Sm ion (0.68 µ B /Sm) and Curie-Weiss like paramagnetic physical properties down to the superconducting critical temperature (T c = 2.8 K) [11,28] highlights a possible unconventional superconductivity in the presence of magnetic ions similar to those for the Pu-based compounds in the R n M m X 3n+2m structure family.…”

“…In Sm 4 Co 3 Ga 16 , additional Co atoms enter as self-interstitials into the parent Sm 2 CoGa 8 structure while keeping the same crystallographic space group [28]. Slightly lowered effective moment of Sm ion (0.68 µ B /Sm) and Curie-Weiss like paramagnetic physical properties down to the superconducting critical temperature (T c = 2.8 K) [11,28] highlights a possible unconventional superconductivity in the presence of magnetic ions similar to those for the Pu-based compounds in the R n M m X 3n+2m structure family. However, no further studies on detail physical properties on this compound have been reported.…”

Putting ScTGa5(T = Fe, Co, Ni) on the Map: How Electron Counts and Chemical Pressure Shape the Stability Range of the HoCoGa5Type

“…One possibility is offered by the Sm 4 Co 3 Ga 12 structure type, in which some T atoms occupy the octahedral holes in AuCu 3 -type slabs of a Ho 2 CoGa 8 -type framework. However, from the stability range of this structure type determined by work of Slater et al, it seems that more extensive insertion interstitials would be necessary to open the cuboctahedra enough to accommodate La or Ce. If nothing else, though, the driving forces revealed here for HoCoGa 5 -type gallides lay out chemical challenges that must be addressed in the search for new members of this series.…”

Interplay of two magnetic sublattices in related compounds Sm2Mn1−xGa6−yGey (x = 0.1–0.3, y = 0.6–1.0) and Sm4MnGa12−yGey (y = 3.0–3.5) with different ordering of empty and filled (Ga,Ge)6 octahedra

“…The first leads to the formation of a structural family of compounds with the general formula R n TGa 3n+2 (n = 1 and 2). [2][3][4][5][6] In the second case, the voids can be filled either stochastically leading to the RT x Ga 3 phases 7,8 or in an ordered fashion creating the R 4 TGa 12 [9][10][11][12][13][14] and R 2 TGa 6 15,16 superstructures.…”