Predicted half-metallicity and ferromagnetism in the Fe (III) doped BaZrO3 perovskite: A theoretical insight

Mohammad Nisar,Yecheng Ma,Gang Xu,Gaorong Han,Rabia Khatoon,Shahid Khan,Yong Liu

doi:10.1063/5.0049191

Abstract

The variance in the magnetoelectric behavior of BaZrO3 owing to the doping of Fe (III) on the Zr-site has been studied based on density functional calculations. We can predict the structural parameters, electronic structure, and ferromagnetic properties of BaFexZr1−xO3 precisely deprived of considering any strong correlation effect in the calculations. The equilibrium structural parameters are accounted to be in concurrence with the former theoretical and experimental investigations. It is observed that the structural phase remained semiconducting cubic (Pm-3m) up to 12.5% of Fe content and transformed to a conducting tetragonal phase (P4/mmm) beyond that. Spin-polarized density of states and band-structure calculations have probed that pristine BaZrO3 is a wide-bandgap semiconductor and in a nonmagnetic state. The ground-energy-state of Fe3+ doped BaZrO3 compounds varies from half-metal to metal in a ferromagnetic state. In particular, the present calculations have correctly predicted half-metallicity in BaFexZr1−xO3 when doping concentrations were 12.5% and 25%. The half-metallic gap ΔHM, which is the minimum of the lowest energy level of minority spin conduction bands relative to the Fermi level, and the absolute values of the topmost energy level of minority spin valence bands are estimated to be 0.55 eV in BaFe0.25Zr0.75O3 and 0.44 eV in BaFe0.5Zr0.5O3.

Highlights

Perovskites are immensely considered materials owing to their extensive diversity of auspicious physical and chemical properties, i.e., superconductivity (Ba1−xKxBiO3),1 charge ordering, multiferroicity (BiFeO3),2 and magnetoresistance (La1−xCaxMnO3).3 Materials that behave as a conductor in one spin channel and as semiconductors or insulators in other channels are called half-metals.4 The half-metallic materials depicted by a 100% level of spin-polarization at the Fermi level are highly desirable, providing pure spins for collateral spin transport and handling due to these novel behaviors, which are thoroughly favorable for spintronic applications
The structure of BFZO remained cubic with space group Pm-3m up to 12.5% of Fe content and transformed to tetragonal (P4/mmm) symmetry for 25% and beyond according to the present density functional theory (DFT) calculations
It is a point to notice that the tetragonality of BFZO increases with the increase in Fe dopant, which can attribute to the increasing distortion due to the imminent of more Fe–O bond lengths

Summary

INTRODUCTION

Perovskites are immensely considered materials owing to their extensive diversity of auspicious physical and chemical properties, i.e., superconductivity (Ba1−xKxBiO3), charge ordering, multiferroicity (BiFeO3), and magnetoresistance (La1−xCaxMnO3). Materials that behave as a conductor in one spin channel and as semiconductors or insulators in other channels are called half-metals. The half-metallic materials depicted by a 100% level of spin-polarization at the Fermi level are highly desirable, providing pure spins for collateral spin transport and handling due to these novel behaviors, which are thoroughly favorable for spintronic applications. All half-metals are always ferromagnetic (or ferrimagnetic), and such a characteristic can be noticed in perovskites, Heusler compounds, and weak magnetic semiconductors.. The half-metallicity exists in numerous perovskites, which are undoubtedly one of the appealingly vibrant families of complex oxides and have a wider variety of properties, to be specific superconductivity (e.g., Ba1−xKxBiO3), massive magnetoresistance (e.g., La1−xCaxMnO3), migratory electron ferromagnetism (e.g., SrRuO3), multiferroic conduct (e.g., TbMnO3), ferroelectricity (e.g., BaTiO3), piezoelectricity (e.g., PbZr1−xTixO3), and ionic conductivity (e.g., La0.67−xLi3xTiO3 and BaCeO3−x), leading into a mixed-valence of half-metallic perovskites among the others. The structural, electronic, and ferromagnetic properties of BaFexZr1−xO3 were studied in detail with a broad doping range, i.e., x = 0.125–0.50. The spin-polarized electronic density of states (DOS) and band structure of state plots reveal that BaFexZr1−xO3 compounds have mostly the half-metallic behavior when the doping content was below 0.25%. In the studies of Fe doped BZO, no experimental or theoretical work on the HM ferromagnetic behavior is available for our best information. This work is expected to accumulate the lack of theoretical information regarding our focused aspects of the under-considered material

COMPUTATIONAL DETAILS

Structural properties

Band structure and density of states

Electron density

CONCLUSIONS