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<p>The structure, electronic, magnetic and optical properties of pyrite CrO<sub>2</sub> at 46 GPa are extensively investigated for the first time using first-principles electronic&#xa0;structure calculations. Structural distortion is observed in the present material due to distortion in the CrO<sub>6</sub> octahedra. The system is found to be half-metallic and ferromagnetic. The two available electrons are found to be distributed among all five Cr-3d orbitals. The three Cr-t<sub>2g</sub> (Cr-d<sub>xy,</sub> d<sub>yz</sub>, d<sub>xz</sub>) as well as the two Cr-e<sub>g</sub> (Cr-3d<sub>3z</sub><sup>2</sup><sub>- r</sub><sup>2</sup>, Cr-3d<sub>x</sub><sup>2</sup><sub>- y</sub><sup>2</sup>) orbitals are observed to&#xa0;be degenerate. The partial filling and delocalization of electrons in all five Cr-3d orbitals for the majority spin channel are responsible for the half-metallic behaviour of pyrite CrO<sub>2</sub>. The simultaneous effect of p-d hybridization and Cr–O antiferromagnetic coupling is responsible for ferromagnetism in the present material. The system remains half-metallic upon the application of U = 3 eV. The strength of ferromagnetism is enhanced at U = 3 eV. The Curie temperature T<sub>c</sub> of pyrite CrO<sub>2</sub> is significantly reduced to 146 K (~156 K for U = 3 eV) at 46 GPa. The metallicity and anisotropy in the structure are observed in the investigation of the real [<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\upvarepsilon }_{1}\left(\upomega \right)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">ε</mi> <mn>1</mn> </msub> <mfenced close=")" open="("> <mi mathvariant="normal">ω</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation>] and imaginary [<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\upvarepsilon }_{2}\left(\upomega \right)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">ε</mi> <mn>2</mn> </msub> <mfenced close=")" open="("> <mi mathvariant="normal">ω</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation>] parts of the dielectric function. In the study of the energy loss function [<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\text{L}\left(\upomega \right)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>L</mtext> <mfenced close=")" open="("> <mi mathvariant="normal">ω</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation>], a significant electron energy loss is observed at a high pressure of 46 GPa. The system exhibits low dissipation or transparency up to 30 eV. The plasmon frequencies observed for <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\({\text{L}}_{\text{xx}}\left(\upomega \right)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>L</mtext> <mtext>xx</mtext> </msub> <mfenced close=")" open="("> <mi mathvariant="normal">ω</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\({\text{L}}_{\text{yy}}\left(\upomega \right)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>L</mtext> <mtext>yy</mtext> </msub> <mfenced close=")" open="("> <mi mathvariant="normal">ω</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\({\text{L}}_{\text{zz}}\left(\upomega \right)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>L</mtext> <mtext>zz</mtext> </msub> <mfenced close=")" open="("> <mi mathvariant="normal">ω</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation>&#xa0;(x-, y- and z-components of [<InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\text{L}\left(\upomega \right)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>L</mtext> <mfenced close=")" open="("> <mi mathvariant="normal">ω</mi> </mfenced> </mrow> </math></EquationSource> </InlineEquation>]) are 26.72, 26.65 and 26.34 eV, respectively, below which the system remains metallic. It is observed that the optical properties do not change substantially upon applying U=3 eV.</p>

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First-principles study of the structure, electronic, magnetic and optical properties of pyrite CrO2 at 46 GPa

  • 期刊论文

  • 发表日期：

    2026年1月20日

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  • S. Biswas

摘要

The structure, electronic, magnetic and optical properties of pyrite CrO2 at 46 GPa are extensively investigated for the first time using first-principles electronic structure calculations. Structural distortion is observed in the present material due to distortion in the CrO6 octahedra. The system is found to be half-metallic and ferromagnetic. The two available electrons are found to be distributed among all five Cr-3d orbitals. The three Cr-t2g (Cr-dxy, dyz, dxz) as well as the two Cr-eg (Cr-3d3z2- r2, Cr-3dx2- y2) orbitals are observed to be degenerate. The partial filling and delocalization of electrons in all five Cr-3d orbitals for the majority spin channel are responsible for the half-metallic behaviour of pyrite CrO2. The simultaneous effect of p-d hybridization and Cr–O antiferromagnetic coupling is responsible for ferromagnetism in the present material. The system remains half-metallic upon the application of U = 3 eV. The strength of ferromagnetism is enhanced at U = 3 eV. The Curie temperature Tc of pyrite CrO2 is significantly reduced to 146 K (~156 K for U = 3 eV) at 46 GPa. The metallicity and anisotropy in the structure are observed in the investigation of the real [ \({\upvarepsilon }_{1}\left(\upomega \right)\) ε 1 ω ] and imaginary [ \({\upvarepsilon }_{2}\left(\upomega \right)\) ε 2 ω ] parts of the dielectric function. In the study of the energy loss function [ \(\text{L}\left(\upomega \right)\) L ω ], a significant electron energy loss is observed at a high pressure of 46 GPa. The system exhibits low dissipation or transparency up to 30 eV. The plasmon frequencies observed for \({\text{L}}_{\text{xx}}\left(\upomega \right)\) L xx ω , \({\text{L}}_{\text{yy}}\left(\upomega \right)\) L yy ω and \({\text{L}}_{\text{zz}}\left(\upomega \right)\) L zz ω  (x-, y- and z-components of [ \(\text{L}\left(\upomega \right)\) L ω ]) are 26.72, 26.65 and 26.34 eV, respectively, below which the system remains metallic. It is observed that the optical properties do not change substantially upon applying U=3 eV.