Small moment antiferromagnetic ordering in single crystalline La₂Ni₇

Specific heat, electrical resistivity, and low field magnetization measurements indicate that there is a series of antiferromagnetic phase transitions at T₁ = 61.0 K, T₂ = 56.5 K and T₃ = 42.2 K in La₂Ni₇ single crystals at ambient pressure. They have very small entropy changes associated with them and the anisotropic M(H) data saturate at ~ 0.12 μ_B/Ni; both observations strongly suggest the AFM order is associated with very small, itinerant, moments. Analysis of M(T), M(H), ρ(T) and ρ(H) data allow for the construction of anisotropic H-T phase diagrams as well as the identification of the two lower temperature magnetically ordered states as antiferromagnetically ordered, with the moments aligned along the c-axis, and the higher temperature, T₂ < T < T₁, state as having a finite ferromagnetic component. Applying pressures up to 2.0 GPa in ρ(T) indicates that there is very little pressure dependence of T₁, T₂ and T₃ over this pressure range.