Magnetic and transport properties of R(Mn, In) 2 (R—rare-earth metals) with AlB 2-structure type

Abstract

We studied the crystal structure and magnetic properties of ternary rare-earth R(Mn,In) 2 compounds (R=Y, La, Ce, Tb–Tm, Lu), which crystallize in the AlB 2-structure type with approximate stoichiometry RMn 0.67In 1.33, but adopting a variable Mn deficiency. YMn 0.92In 1.08 orders antiferromagnetically below T N ≈ 247 K, CeMn 0.65In 1.35 is ferromagnetic with T C=134 K. The compounds with magnetic rare earths tend to a glassy magnetic state, presumably due to the disorder in the Mn/In sublattice together with competing exchange interactions. The disorder has also a dramatic impact on the temperature dependence of the electrical resistivity, which is rather flat due to a strong scattering. The absence of long-range order was proved also by specific-heat measurements. Hydrogen absorption, tested for several compounds, led to the synthesis of LaMn 0.49In 1.51H 0.75(5).