Detuning the Honeycomb of $\alpha$-RuCl${}_3$: Pressure-Dependent Optical Studies Reveal Broken Symmetry

Abstract

The honeycomb Mott insulator $\alpha$-RuCl${}_3$ loses its low-temperature magnetic order by pressure. We report clear evidence for a dimerized structure at $P>1$ GPa and observe the breakdown of the relativistic $j_{\mathrm{eff}}$ picture in this regime strongly affecting the electronic properties. A pressure-induced Kitaev quantum spin liquid cannot occur in this broken symmetry state. We shed light on the new phase by broad-band infrared spectroscopy of the low-temperature properties of $\alpha$-RuCl${}_3$ and ab initio density functional theory calculations, both under hydrostatic pressure.

arXiv comment5 pages, 4 figures

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• Thermodynamic evidence of fractionalized excitations in α-RuCl3
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• Role of Hydrogen in the spin-orbital-entangled quantum liquid candidate H${}_3$LiIr${}_2$O${}_6$
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• Chemical- and hydrostatic-pressure effects on the Kitaev honeycomb material Na${}_2$IrO${}_3$
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• Multiple Spin-Orbit Excitons and the Electronic Structure of $\alpha$-RuCl${}_3$
• Optical signature of the pressure-induced dimerization in the honeycomb iridate $\alpha$-Li${}_2$IrO${}_3$
• Pressure-induced formation of rhodium zigzag chains in the honeycomb rhodate Li${}_2$RhO${}_3$
• Sub-gap optical response across the structural phase transition in van der Waals layered α-RuCl${}_3$
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• Hydrostatic pressure effect on Co-based honeycomb magnet BaCo2(AsO4)2
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• First-principles design of the spinel iridate Ir2O4 for high-temperature quantum spin ice
• Honeycomb lattice iridate on the verge of Mott-collapse