Effects of IIIB transition metals on optoelectronic and magnetic properties of HoMnO3: A first principles study

The optoelectronic and magnetic properties of pure HoMnO3 and Ho0.67T0.33MnO3 (T = La, Y) alloys in hexagonal phase are theoretically investigated by using the first-principles calculations. The investigations are performed by means of the density functional theory through using the spin polarized generalized gradient approximation plus the Hubbard potential (SPGGA + U, Ueff = 3 eV). The studied material HoMnO3 exhibits two indirect band gaps: 1.58 eV for the spinup state and 0.72 eV for the spin-down state along the S-G direction within the SPGGA + U approximation. It is found that the band gap of pure HoMnO3 for the spin-up state increases with increasing La and Y dopants. The results show that all of the studied materials have semi-metallic behaviors for the spin-up state and semiconducting character for the spin-down state. The substitutions of La and Y for Ho in HoMnO3 cause the static dielectric constant (epsilon(0)) to increase in the x direction but to decrease in the z direction. The calculated optical conductivity spectrum of HoMnO3 in a low energy range is in good agreement with the recent experimental data