Spin-orbital entangled state and realization of Kitaev physics in 3d cobalt compounds: a progress report

Abstract

The realization of Kitaev's honeycomb magnetic model in real materials has become one of the most pursued topics in condensed matter physics and materials science. If found, it is expected to host exotic quantum phases of matter and offers potential realizations of fault$-$tolerant quantum computations. Over the past years, much effort was made on 4d$-$ or 5d$-$ heavy transition metal compounds because of their intrinsic strong spin$-$orbit coupling. But more recently, there have been growing shreds of evidence that the Kitaev model could also be realized in 3d$-$transition metal systems with much weaker spin$-$orbit coupling. This review intends to serve as a guide to this fast$-$developing field focusing on systems with d${}^7$ transition metal occupation. It overviews the current theoretical and experimental progress on realizing the Kitaev model in those systems. We examine the recent experimental observations of candidate materials with Co${}^{2+}$ ions: e.g., CoPS${}_3$, Na${}_3$Co${}_2$SbO${}_6$, and Na${}_2$Co${}_2$TeO${}_6$, followed by a brief review of theoretical backgrounds. We conclude this article by comparing experimental observations with density functional theory (DFT) calculations. We stress the importance of inter$-t_{2g}$ hopping channels and Hund's coupling in the realization of Kitaev interactions in Co$-$based compounds, which has been overlooked in previous studies. This review suggests future directions in the search for Kitaev physics in 3d cobalt compounds and beyond.

arXiv comment45 pages, 13 figures, accepted as Topical Review in Journal of Physics: Condensed Matter

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Cited by in corpus (38)

• Excitations in the ordered and paramagnetic states of honeycomb magnet Na2Co2TeO6
• Dominant Kitaev interactions in the honeycomb materials Na${}_3$Co${}_2$SbO${}_6$ and Na${}_2$Co${}_2$TeO${}_6$
• A magnetic continuum observed by terahertz spectroscopy in a quantum spin liquid candidate BaCo${}_2$(AsO${}_4$)${}_2$
• Beyond Kitaev physics in strong spin-orbit coupled magnets
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• Giant magnetic in-plane anisotropy and competing instabilities in Na3Co2SbO6
• Non-Kitaev vs. Kitaev Honeycomb Cobaltates
• Significant thermal Hall effect in the 3$d$ cobalt Kitaev system $N{a}_{2}C{o}_{2}Te{O}_6$
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• Ground-state phase diagram of spin-$S$ Kitaev-Heisenberg models
• Easy-plane multi-$\mathbf{q}$ magnetic ground state of Na${}_3$Co${}_2$SbO${}_6$
• Spin wave spectra of single crystal CoPS${}_3$
• Spin dynamics of the generalized quantum spin compass chain
• Signatures of Kitaev interactions in the van der Waals ferromagnet VI3
• Comparative Raman Scattering Study of Crystal Field Excitations in Co-based Quantum Magnets
• Field and Polarization Dependent Quantum Spin Dynamics in Honeycomb Magnet Na${}_2$Co${}_2$TeO${}_6$: Magnetic Excitations and Continuum
• Field-induced phase transitions and quantum criticality in a honeycomb antiferromagnet Na3Co2SbO6
• Anomalous continuum scattering and higher-order van Hove singularity in the strongly anisotropic S = 1/2 triangular lattice antiferromagnet
• Persistent spin dynamics in magnetically ordered honeycomb cobalt oxides
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• Ground-State Phase Diagram of the Kitaev-Heisenberg Model on a Three-dimensional Hyperhoneycomb Lattice
• BaCo${}_2$(AsO${}_4$)${}_2$: Strong Kitaev, After All
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