Properties of RRe₂Al₁₀ (R=Y, Gd–Lu) crystals

Large single crystals of rare-earth rhenium aluminide RRe₂Al₁₀, with R=Y, and Gd–Lu were grown out of an Al-rich solution. Single crystal x-ray diffraction data confirmed the orthorhombic Cmcm structure for all members: R=Gd-Dy with TbRe₂Al₁₀-structure type (formula unit per cell Z=8); R=Y, and Ho–Lu with LuRe₂Al₁₀-structure type (Z=12). There is no evidence of a localized 3d electron moment in R=Y and Lu; R=Yb is nonmagnetic down to 1.8 K, but develops an enhanced electronic specific heat of ∼95 mJ mol⁻¹ K⁻². Ordering temperatures range from ferromagnetic order in R=Gd with T_c=7.2(1) K, antiferromagnetic order in R=Tb at T_N=5.0(3) K, to R=Dy, Ho, and Er giving magnetic ordering temperatures of T_mag=1.7(1), ≤0.4, and 1.1(2) K, respectively. All compounds have effective moments close in value to that of free R³⁺ at high temperatures.