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arXiv · 2204.12403

Magnetic Excitations and Interactions in the Kitaev Hyperhoneycomb Iridate $\beta$-Li$_2$IrO$_3$

Thomas Halloran·Yishu Wang·Mengqun Li·Ioannis Rousochatzakis·Prashant Chauhan·M. B. Stone·Tomohiro Takayama·Hidenori Takagi·N. P. Armitage·Natalia B. Perkins·Collin Broholm
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Abstract

We present a thorough experimental study of the three-dimensional hyperhoneycomb Kitaev magnet $\beta$-Li$_2$IrO$_3$, using a combination of inelastic neutron scattering (INS), time-domain THz spectroscopy, and heat capacity measurements. The main results include a massive low-temperature reorganization of the INS spectral weight that evolves into a broad peak centered around 12 meV, and a distinctive peak in the THz data at 2.8(1) meV. A detailed comparison to powder-averaged spin-wave theory calculations reveals that the positions of these two features are controlled by the anisotropic $\Gamma$ coupling and the Heisenberg exchange $J$, respectively. The refined microscopic spin model places $\beta$-Li$_2$IrO$_3$ in close proximity to the Kitaev spin liquid phase.

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Thomas Halloran, Yishu Wang, Mengqun Li, Ioannis Rousochatzakis, Prashant Chauhan, M. B. Stone, Tomohiro Takayama, Hidenori Takagi, N. P. Armitage, Natalia B. Perkins, Collin Broholm. 2022-04-26. Magnetic Excitations and Interactions in the Kitaev Hyperhoneycomb Iridate $\beta$-Li$_2$IrO$_3$. https://doi.org/10.1103/physrevb.106.064423

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