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arXiv · 2411.11146

Tunable Dirac nodal line in orthorhombic RuO$_2$

Ece Uykur·Oleg Janson·Victoria A. Ginga·Marcus Schmidt·Nico Giordano·Alexander A. Tsirlin
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Abstract

Pressure evolution of RuO2 is studied using single-crystal x-ray diffraction in a diamond anvil cell, combined with \textit{ab initio} band-structure calculations. The tetragonal rutile structure transforms into the orthorhombic CaCl$_2$-type structure above 13 GPa under quasi-hydrostatic pressure conditions. This second-order transition is ferroelastic in nature and accompanied by tilts of the RuO$_6$ octahedra. Orthorhombic RuO$_2$ is expected to be paramagnetic metal, similar to ambient-pressure RuO$_2$. It shows the increased $t_{2g}-e_g$ crystal-field splitting that is responsible for the pressure-induced color change. It further features the Dirac nodal line that shifts across the Fermi level upon compression.

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Ece Uykur, Oleg Janson, Victoria A. Ginga, Marcus Schmidt, Nico Giordano, Alexander A. Tsirlin. 2024-11-17. Tunable Dirac nodal line in orthorhombic RuO$_2$. https://arxiv.org/abs/2411.11146

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