Ab initio study including spin-orbit coupling of the electronic band structure and magnetic properties of h-HoMnO3

A theoretical investigation of the structural, electronic, magnetic, and magneto-elastic properties is provided for the non-perovskite HoMnO3 in low symmetry. This study has been carried out using density functional theory (DFT + U) with the inclusion of the polarized spin and spin-orbit coupling for both ferromagnetic and antiferromagnetic configurations. The generalized gradient approximation (GGA), the GGA + U, and modified Becke-Johnson (mBJ) approach have been used. The stability of the ground state of this compound in ferromagnetic (FM) and antiferromagnetic (AFM) configurations has been highlighted, confirming the magnetic behavior of HoMnO3. A good agreement has been observed between the internal atomic relaxation calculations and the experimental data. The calculated total magnetic moment of HoMnO3, localized on Ho atom is about ~ 9.6 µB for the ferromagnetic configuration, in good agreement with the available experimental data. On other hand, the GGA and GGA + U (where U ~ 7 eV) approximations have predicted a metallic behavior behavior for the h-HoMnO3, whereas, the implementation of mBJ approach has highlighted a semiconductor feature of the HoMnO3 with spin-polarized band gap about 0.5 eV (FM) and 0.6 eV (AFM). The calculated Bulk modulus has been found to be about 162.23 GPa (FM), and 169.34 GPa (AFM).