DFT Study on Metamagnetics β-M (OH)2 (M = Mn, Fe, Co, Ni)

First-principles calculations have been carried out in order to analyze the structural, vibrational, and magnetic properties in the A-type antiferromagnetic (AFM) beta-M(OH)(2) metal transition hydroxides. Theoretical results demonstrate a quasi layer-by-layer magnetic behavior with strong ferromagnetic (FM) interactions in the intralayer plane and weak AFM behavior between the interlayer. This behavior corresponds to an A-type AFM behavior for beta-M(OH)(2) (M = Mn, Fe, Co, and Ni) with energy differences around 3.0 meV with respect to the FM state. Structural analysis reveal a clear influence of Van der Waals (VdW) interactions in the stabilization of the phase giving high accuracy in lattice parameter when compared to experimental findings. Qualitative analysis of the magnetic exchange interactions reveals a higher exchange intralayer interaction for M = Ni, and higher exchange or dipolar interlayer interactions for M = Mn. Vibrational analysis, in the M = Ni case, demonstrate a correct IR and Raman modes assignments according to experimental results on the P (3) over bar m1 space group.