Linear magnetoelectricity in the Zintl phase pnictides (Ba, Ca, Sr) Mn₂ (P, As, Sb)₂ from first-principles calculations

We report a comprehensive set of density functional theory calculations on the family of layered antiferromagnetic manganese pnictides (Ba,Ca,Sr)Mn₂(P,As,Sb)₂. We characterize all components to the linear magnetoelectric (ME) tensor α, which are parsed into their contributions from spin and orbital moments for both lattice-mediated and their clamped-ion electronic analogs. Our main results show that the orbital magnetization components cannot be neglected in these systems. The ME response is dominated by electronic effects with total α values exceeding those of the prototypical Cr₂O₃ (i.e., α≃6.79 ps/m in BaMn₂As₂). We also identify a strong correlation with the computed ME susceptibility on pnictogen substitution in the trigonal subfamily albeit with weaker amplitudes (α≈0.2-1.7 ps/m). Additionally, we provide the dependence of these predictions on the Hubbard +U correction, at the level of the local density approximation, which shows large variations on the calculated ME coefficients in the tetragonal compounds highlighting the role of strong correlation in these compounds.