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arXiv · 2403.17085

Magnetic versus nonmagnetic polymorphs of RuBr$_3$ under pressure

Bin Shen·Victoria A. Ginga·Angel M. Arévalo-López·Gaston Garbarino·Ece Uykur·Marcos Goncalves-Faria·Prashanta K. Mukharjee·Philipp Gegenwart·Alexander A. Tsirlin
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Abstract

Pressure evolution of the crystal structure and magnetism of the honeycomb $\alpha$-RuBr$_3$ is studied using high-pressure x-ray diffraction, magnetometry, and density-functional band-structure calculations. Hydrostatic compression transforms antiferromagnetic $\alpha$-RuBr$_3$ ($R\bar 3$) into paramagnetic $\alpha'$-RuBr$_3$ ($P\bar 1$) where short Ru-Ru bonds cause magnetism collapse above 1.3 GPa at 0 K and 2.5 GPa at 295 K. Below this critical pressure, the N\'eel temperature of $\alpha$-RuBr$_3$ increases with the slope of 1.8 K/GPa. Pressure tunes $\alpha$-RuBr$_3$ away from the Kitaev limit, whereas increased third-neighbor in-plane coupling and interlayer coupling lead to a further stabilization of the collinear zigzag state. Both $\alpha$- and $\alpha'$-RuBr$_3$ are metastable at ambient pressure, but their transformation into the thermodynamically stable $\beta$-polymorph is kinetically hindered at room temperature.

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Bin Shen, Victoria A. Ginga, Angel M. Arévalo-López, Gaston Garbarino, Ece Uykur, Marcos Goncalves-Faria, Prashanta K. Mukharjee, Philipp Gegenwart, Alexander A. Tsirlin. 2024-03-25. Magnetic versus nonmagnetic polymorphs of RuBr$_3$ under pressure. https://doi.org/10.1103/physrevb.109.224402

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