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| Main Author: | |
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| Format: | Preprint |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2307.04584 |
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Table of Contents:
- A stable polymorph of CrO$_2$ is predicted using PBE+U method. The porous material is isostructural with $α-$MnO$_2$ making it the second transition metal oxide in sparse hollandite group of materials. However, unlike the anti-ferromagnetic semiconducting character of the $α-$MnO$_2$, it is found to be a ferromagnetic half-metal. At Fermi level, the hole pocket has ample contribution from O$-2p$ orbital, though, the electron pocket is mostly contributed by Cr$-3d_{xy}$ and Cr$-3d_{x^2-y^2}$. A combination of negative charge transfer through orbital mixing and extended anti-bonding state near Fermi level is responsible for the half-metallic ferromagnetic character of the structure. A comparative study of rutile and hollandite CrO$_2$ and hollandite MnO$_2$ structures delineate the interplay between structural, electronic and magnetic properties. The material shows a robust magnetic character under hydrothermal pressure, as well as, the band topology is conserved under uniaxial strain. Moderate magneto-crystalline anisotropy is observed and it shows a correspondence with the anisotropy of elastic constants. Occurrence of type$-$II Weyl nodes and their evolution under pressure is explored.