Influence of the transition-metal substitution on the physical properties of Lu 2− xNi 21B 6 – From Pauli-paramagnetism to weak ferromagnetism

Abstract

The ternary boride Lu 2− x Ni 21B 6 crystallizes with the Cr 23B 6 structure type (space group Fm 3 ¯ m, a = 10.6256(2)). It is a Pauli paramagnet with a rather large temperature-independent contribution of χ 0 = 1.7 × 10 −3 emu/mol and an effective moment μ eff = 1.5 μ B/f.u. Density functional calculations performed for Lu 2Ni 21B 6 showed that hole doping could lead to band magnetism, while light electron doping should suppress the tendency toward magnetic order. Both predictions are confirmed experimentally: Lu 1.65Ni 17.5Co 3.5B 6 is a weak itinerant soft ferromagnet with T C ≈ 39 K, an effective paramagnetic moment μ eff = 5.86 μ B/f.u., and a Weiss temperature θ W = +71 K, while Lu 1.65Ni 20.75Cu 0.25B 6 and Lu 1.35Y 0.3Ni 21B 6 are Pauli paramagnets with rather small Curie-like contributions at low temperatures.