Density functional investigation of the magnetic superstructure of Cu2MnSnS4

The cause for the ordered magnetic structure of Cu2MnSnS4 below TN=8.8 K was examined by evaluating the spin exchange interactions on the basis of density functional electronic structure calculations. The Mn–S…S–Mn super-superexchange interactions of Cu2MnSnS4 are all calculated to be antiferromagnetic. In the (2a, b, 2c) magnetic superstructure observed from the neutron diffraction, only one spin exchange contributes to the energy lowering. This makes the (2a, b, c) antiferromagnetic superstructure identical in energy with the (2a, b, 2c) antiferromagnetic superstructure, implying that the magnetic Bragg peaks of Cu2MnSnS4 below TN have contributions from both (2a, b, c) and (2a, b, 2c) superstructures.