Thermodynamics evaluation of half-metallic ferromagnetism in N-doped XTiO3 (X = Ca, Sr, and Ba) systems: DFT calculations

Abstract

Half-metallic (HM) materials with high magnetic transition temperature (TC) combined with a wide energy gap (Eg) in insulating spin channel are desired for the realization of modern spin based devices due to their stable ferromagnetic (FM) ordering, spin-filtering, and high mean free path. Herein, the formation energetics, electronic, and magnetic characteristics of N-doped XTiO3 (XTO) (X = Ca, Sr, and Ba) perovskite oxides (PO) were inspected by first-principles calculations, where one of the oxygen (O) atom is replaced by nitrogen (N) atom. The calculated formation energy and elastic constants values confirm the thermodynamical as well as elastic stability of all doped systems. Our calculations show that all undoped PO systems display a non-magnetic insulating behavior. On the other hand, all doped motifs show magnetic character with an integral induced magnetic moment of 1.00 μB. Further, it has also been observed that magnetism in all these doped systems mainly originates from p orbitals of the dopant N. Interestingly, all doped systems have 100% spin splitting at Fermi level depicting a HM FM behavior with large Eg of 1.61, 1.65, and 1.59 eV in spin minority channels for XTO (X = Ca, Sr, and Ba) systems, respectively. Further, a long range stable FM ordering with TC > RT is predicted in these doped materials by computing the magnetic energy solutions for FM and anti-ferromagnetic (AFM) ordering at various distances between two N atoms. The current study suggests that doping strategy with non-magnetic dopant in different PO materials could be a useful approach to modulate the physical features and make them effective for emerging spintronic devices operating above RT.