Robust half-metallicity of hexagonal SrNiO3

• Hexagonal SrNiO3 is studied using first-principles method for the first time.
• It is predicted that SrNiO3 is a ferromagnetic half metal.
• The half-metallic ferromagnetism survives upon a pressure up to 20 GPa.

In the rich panorama of the electronic and magnetic properties of 3d transition metal oxides SrMO3 (M=Ti, V, Cr, Mn, Fe, Co, Ni, Cu), one member (SrNiO3) is missing. In this paper we use GGA+U method based on density functional theory to examine its properties. It is found that SrNiO3 is a ferromagnetic half-metal. The charge density map shows a high degree of ionic bonding between Sr and other atoms. Meanwhile, a covalent-bonding Ni–O–Ni–O–Ni chain is observed. The spin density contour of SrNiO3 further indicates that the magnetic interaction between Ni atoms mediated by O is semicovalent exchange. The density of states are examined to explore the unusual indirect magnetic-exchange mechanism. Corresponding to the total energies results, a robust half-metallic character is observed, suggesting a promising giant magneto-optical Kerr property of the material. The partial density of states are further examined to explore the origin of ferromagnetic half-metallicity. The O atoms are observed to have larger contribution at fermi level than Ni atoms to the spin-polarized states, demonstrating that O atoms play a critical role in ferromagnetic half-metallicity of SrNiO3. Hydrostatic pressure effect is examined to evaluate how robust the half-metallic ferromagnetism is.

(a) The total energy as a function of the lattice constant a for hexagonal SrNiO3 with various magnetic phases. (b) The total electronic density of states for hexagonal SrNiO3 with FM configuration from GGA+U calculations. (c) Total electron-density distribution in the (110) plane. The colors gradually change from cyan (through pink) to yellow corresponding to charge density value from 0 to 4.0. (d) The magnetization density map in the (110) plane. The colors range from blue (through green) to red corresponding to magnetization density value from −0.15 to 0.45. Black and white contours stand for positive and negative values, respectively.Figure optionsDownload as PowerPoint slide