Theoretical calculation of structural, electronic, magnetic, and thermoelectric properties of KMO2 (M = Sm3+, Tb3+, and Dy3+) oxides by ab initio method.

Structural, electronic, optical, thermoelectric and magnetic characteristics of potassium-based rare earth oxides are discussed in this paper. Density-functional theory (DFT) based on a full-potential linear augmented plane wave plus local orbital (FP-LAPW + lo) system within Wien2k software; for the exchange-correlation energy (PBE + GGA) approximation was carried out. Crystal structures of these materials have a hexagonal form with a space group (166_R-3m). Therefore, volume-optimized graph results depicted that studied compounds are more energetically stable in ferromagnetic states than in anti-ferromagnetic and non-magnetic states. Moreover, spin polarize band structure and Density of States (DOS) of studied materials shows metallic and semiconductor nature for corresponding spin channels. However, studied materials have half metallic nature with 100% spin polarization at EF. Total and partial magnetic moments of KMO2 and individual atoms existed due to lanthanide ions due to unpaired 4f electronic states that are present at Fermi level EF. Finally, the energy difference between anti-ferromagnetism and ferromagnetism energy versus volume optimization curve gives the value of Curie temperature TC and noticed that room temperature ferromagnetism is possible.