The magnetic properties of MAl 4 (OH) 12 SO 4 ·3H 2 O with M = Co 2+ , Ni 2+ , and Cu 2+ determined by a combined experimental and computational approach.

The magnetic properties of the nickelalumite-type layered double hydroxides (LDH), MAl 4 (OH) 12 (SO 4 )·3H 2 O (MAl 4 -LDH) with M = Co 2+ ( S = 3/2), Ni 2+ ( S = 1), or Cu 2+ ( S = 1/2) were determined by a combined experimental and computational approach. They represent three new inorganic, low-dimensional magnetic systems with a defect-free, structurally ordered magnetic lattice. They exhibit no sign of magnetic ordering down to 2 K in contrast to conventional hydrotalcite LDH. Detailed insight into the complex interplay between the choice of magnetic ion (M 2+ ) and magnetic properties was obtained by a combination of magnetic susceptibility, heat capacity, neutron scattering, solid-state NMR spectroscopy, and first-principles calculations. The NiAl 4 - and especially CoAl 4 -LDH have pronounced zero-field splitting (ZFS, easy-axis and easy-plane, respectively) and weak ferromagnetic nearest-neighbour interactions. Thus, they are rare examples of predominantly zero-dimensional spin systems in dense, inorganic matrices. In contrast, CuAl 4 -LDH ( S = 1/2) consists of weakly ferromagnetic S = 1/2 spin chains. For all three MAl 4 -LDH, good agreement is found between the experimental magnetic parameters ( J , D , g ) and first-principles quantum chemical calculations, which also predict that the interchain couplings are extremely weak (< 0.1 cm -1 ). Thus, our approach will be valuable for evaluation and prediction of magnetic properties in other inorganic materials.