Investigation of thermodynamical stability and generation of large half-metallic gap along with optical properties in N-doped YHfO3 (YHO) (Y = Ca, Sr, and Ba) perovskite materials by first principle calculations

Abstract

Considerable energy gap (Eg) in insulating channel, high spin-filtering, significant mean free path, and high magnetic transition temperature (TC) escalate half-metallic (HM) ferromagnetic (FM) materials very enticing for spintronic applications. Herein, ab-initio calculations have been executed comprehensively to inquest the structural, thermodynamical, electronic, magnetic, and optical properties of pure as well as nitrogen (N)-doped YHfO3 (YHO) (Y = Ca/Sr/Ba) materials with one N atom added at one of the oxygen (O) site. First, the thermodynamical stability of both bulk and doped YHO systems has been examined by estimating the formation enthalpies (ΔHf) by Convex Hull analysis, which confirms the practical realization of these materials on experimental grounds. Moreover, mechanical stability of these systems is affirmed by estimating the necessary elastic constants and respective parameters. Strikingly, all doped systems possess complete (100%) splitting in spin↑ and spin↓ channels at Fermi level and depict HM FM character with significant Eg of 3.31, 3.49, and 3.24 eV in spin↓ channels for CaHO (CHO), SrHO (SHO), and BaHO (BHO) systems, respectively. It is also found that N 2p orbitals are totally responsible for the emergence of metatallicity and magnetic character in all these doped structures. Moreover, the ground state long range FM stability between two added N atoms in doped systems is affirmed by computing the difference of total energies of FM and anti-ferromagnetic (AFM) spin ordering (ΔE) along with estimated TC at different distances. Lastly, it is found that N-doped systems have a lower optical energy loss than pristine YHO systems in the incident photon energy range of 0-50 eV. Hence, the present study proposes that an unconventional doping approach with intrinsically non-magnetic element in a variety of YHO perovskite systems could be a useful method to alter their various physical properties and forecast their potential applications in the development of novel spintronic and optoelectronic devices.