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.

45 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
• Magnetic ground state of the Kitaev Na${}_2$Co${}_2$TeO${}_6$ spin liquid candidate
• 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 $N{a}_{2}C{o}_{2}Te{O}_6$
• Ultrafast laser-induced spin-lattice dynamics in the van der Waals antiferromagnet CoPS3
• 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
• Active orbital degree of freedom and potential spin-orbit-entangled moments in Kitaev magnet candidate BaCo${}_2$(AsO${}_4$)${}_2$
• Suppression of the antiferromagnetic order by Zn doping in a possible Kitaev material Na${}_2$Co${}_2$TeO${}_6$
• Ground-State Phase Diagram of the Kitaev-Heisenberg Model on a Three-dimensional Hyperhoneycomb Lattice
• BaCo${}_2$(AsO${}_4$)${}_2$: Strong Kitaev, After All
• Static magnetic and ESR spectroscopic properties of the dimer-chain antiferromagnet BiCoPO${}_5$
• On the multi-$\mathbf{q}$ characteristics of magnetic ground states of honeycomb cobalt oxides
• Hydrostatic pressure effect on Co-based honeycomb magnet BaCo2(AsO4)2
• Intermediate field-induced phase of the honeycomb magnet BaCo${}_2$(AsO${}_4$)${}_2$
• Signatures of a gapless quantum spin liquid in the Kitaev material Na${}_3$Co${}_{2-x}$Zn${}_x$SbO${}_6$
• Field-induced magnetic phases in the Kitaev candidate Na${}_3$Co${}_2$SbO${}_6$
• Topological Majorana flat bands in the Kitaev model on a Bishamon-kikko lattice
• Phenomenological Ginzburg-Landau theory for triple-Q magnetic orders on a hexagonal lattice
• Field-induced phase transitions in the Kitaev-Heisenberg model: A sign-problem-free quantum Monte Carlo study and possible application to $\alpha$-RuCl3
• Magnetostriction in the $J$-$K$-$\Gamma$ model: Application of the numerical linked cluster expansion
• Quantum spin dynamics of the honeycomb magnet K${}_2$Co${}_2$TeO${}_6$ in high magnetic fields
• Trigonal distortion in the Kitaev candidate honeycomb magnet BaCo2(AsO4)2
• Ising spin ladders of orthopyroxene CoGeO${}_3$
• Magnetic field effects on the Kitaev model coupled to environment
• Spin disorder state induced by Mg${}^{2+}$ doping in a Kitaev material Na${}_3$Co${}_2$SbO${}_6$