Band structure and magnetic properties of quasi-one-dimensional antiferromagnet (TrMA)MnCl3 × 2H2O.

The first-principles calculations of the band structure and magnetic properties of trimethylammonium trichloromanganate dehydrate [(CH₃)₃NH]MnCl₃ × 2H₂O crystal within the density functional theory were carried out for the first time. This compound corresponds to the AMeCl₃ crystal groups that are intensively studied experimentally due to their unique magnetic properties at low temperatures. To overcome the electronic correlations associated with the availability of Mn atoms in the crystal structure, the Hubbard-like method (GGA + U) was adopted for our calculations. The U parameter was adjusted to reproduce the nearest-neighbor exchange coupling constant. Also, the behavior of the exchange interaction in charge of magnetic character is analyzed. The different magnetic configurations were examined for finding the ground state. The most energy favorable state for [(CH₃)₃NH]MnCl₃ × 2H₂O is the antiferromagnetic state with spin-ordering that corresponds to C-type AFM (nearest spins in 1D-chains are antiparallelly aligned). The band structure calculations demonstrate the flatness of the band energy dispersion in the valence band. The presented theoretical results confirm the existent experimental data. Especially, the value of the Neel temperature calculated based on the obtained exchange interaction parameter of [(CH₃)₃NH]MnCl₃ × 2H₂O compound corresponds to the experimental one. [ABSTRACT FROM AUTHOR]