Antiferromagnetic Kitaev interactions in polar spin-orbit Mott insulators

Sugita, Yusuke; Kato, Yasuyuki; Motome, Yukitoshi

doi:10.1103/physrevb.101.100410

Cited by 21 publications

(11 citation statements)

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“…Figure 4(c) shows the coupling constants on the modulated bond as functions of the ligand displacement d Cl . For d Cl = 0, the system has the predominant FM Kitaev coupling K and the subdominant positive symmetric off-diagonal coupling Γ, consistent with the previous studies [54,69,70]. When we introduce the displacement d Cl , the inversion symmetry is broken and the DM coupling D is induced as expected.…”

Section: B Case Study Of α-Rucl3: Ligand Displacementsupporting

confidence: 88%

“…We compute how the ligand displacement modulates the exchange interactions between the Ru cations by calculating the electronic structure of the modulated α-RuCl 3 by the ab initio calculations, constructing the multiorbital Hubbard model with the maximally-localized Wannier functions [51,52], and performing the perturbation expansion in the limit of strong correlation. Similar procedure has been adopted for other Kitaev candidates without bond modulations [53][54][55][56].…”

Section: B Case Study Of α-Rucl3: Ligand Displacementmentioning

confidence: 99%

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Vortex creation and control in the Kitaev spin liquid by local bond modulations

Jang,

Kato,

Motome

2021

Preprint

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The Kitaev model realizes a quantum spin liquid where the spin excitations are fractionalized into itinerant Majorana fermions and localized Z2 vortices. Quantum entanglement between the fractional excitations can be utilized for decoherence-free topological quantum computation. Of particular interest is the anyonic statistics realized by braiding the vortex excitations under a magnetic field. Despite the promising potential, the practical methodology for creation and control of the vortex excitations remains elusive thus far. Here we theoretically propose how one can create and move the vortices in the Kitaev spin liquid. We find that the vortices are induced by a local modulation of the exchange interaction; especially, the local Dzyaloshinskii-Moriya (symmetric offdiagonal) interaction can create vortices most efficiently in the (anti)ferromagnetic Kitaev model, as it effectively flips the sign of the Kitaev interaction. We test this idea by performing the ab initio calculation for a candidate material α-RuCl3 through the manipulation of the ligand positions that breaks the inversion symmetry and induces the local Dzyaloshinskii-Moriya interaction. We also demonstrate a braiding of vortices by adiabatically and successively changing the local bond modulations.

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Section: B Case Study Of α-Rucl3: Ligand Displacementsupporting

confidence: 88%

Section: B Case Study Of α-Rucl3: Ligand Displacementmentioning

confidence: 99%

Vortex creation and control in the Kitaev spin liquid by local bond modulations

Jang,

Kato,

Motome

2021

Preprint

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“…They also give rise to an extended intermediate-field strength regime that -despite the generic formation of a conventional ground state with canted magnetic moments for most lattice geometries -exhibits proximate spin liquid behavior in its finite-temperature and finiteenergy observables. A route towards the experimental exploration of such AFM Kitaev materials has been laid out theoretically, identifying 4f materials 62,63 as well as spin-1 Kitaev materials 64,65 as alternatives to the current family of 4d/5d spin-orbit entangled j = 1/2 Mott insulators that have predominantly FM Kitaev couplings [66][67][68][69] .…”

Section: Discussionmentioning

confidence: 99%

Generic Field-Driven Phenomena in Kitaev Spin Liquids: Canted Magnetism and Proximate Spin Liquid Physics

Hickey,

Gohlke,

Berke

et al. 2020

Preprint

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Topological spin liquids in two spatial dimensions are stable phases in the presence of a small magnetic field, but may give way to field-induced phenomena at intermediate field strengths. Sandwiched between the lowfield spin liquid physics and the high-field spin-polarized phase, the exploration of magnetic phenomena in this intermediate regime however often remains elusive to controlled analytical approaches. Here we numerically study such intermediate-field magnetic phenomena for two representative Kitaev models (on the square-octagon and decorated honeycomb lattice) that exhibit either Abelian or non-Abelian topological order in the low-field limit. Using a combination of exact diagonalization and density matrix renormalization group techniques, as well as linear spin-wave theory, we establish the generic features of Kitaev spin liquids in an external magnetic field. While ferromagnetic models typically exhibit a direct transition to the polarized state at a relatively low field strength, antiferromagnetic couplings not only substantially stabilizes the topological spin liquid phase, but generically lead to the emergence of a distinct field-induced intermediate regime, separated by a crossover from the high-field polarized regime. Our results suggest that, for most lattice geometries, this regime generically exhibits significant spin canting, antiferromagnetic spin-spin correlations, and an extended proximate spin liquid regime at finite temperatures. Notably, we identify a symmetry obstruction in the original honeycomb Kitaev model that prevents, at least for certain field directions, the formation of such canted magnetism without breaking symmetries -consistent with the recent numerical observation of an extended gapless spin liquid in this case.

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“…We construct the MLWFs of Ir 5d t 2g and O 2p orbitals for MgIrO 3 and of Zn 3d, Ir 5d t 2g , and O 2p orbitals for ZnIrO 3 for the obtained electronic band structures by using WANNIER90 [42]. Note that, in most of the previous studies for other Kitaev candidate materials, the MLWF analyses were performed only for the 5d or 4d t 2g orbitals [24,26,27,51,52]. In the present study, however, we include O 2p for both MgIrO 3 and ZnIrO 3 and also Zn 3d, since we find that they overlap with Ir 5d t 2g (see Sec.…”

Section: Methodsmentioning

confidence: 99%

Electronic and magnetic properties of iridium ilmenites $A$IrO$_3$ ($A=$ Mg, Zn, and Mn)

Jang,

Motome

2021

Preprint

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We theoretically investigate the electronic band structures and magnetic properties of ilmenites with edge-sharing IrO6 honeycomb layers, AIrO3 with A = Mg, Zn, and Mn, in comparison with a collinear antiferromagnet MnTiO3. The compounds with A = Mg and Zn were recently reported in Y. Haraguchi et al., Phys. Rev. Materials 2, 054411 (2018), while MnIrO3 has not been synthesized yet but the honeycomb stacking structure was elaborated in a superlattice with MnTiO3 in K. Miura et al., Commun. Mater. 1, 55 (2020). We find that, in contrast to MnTiO3, where an energy gap opens in the Ti 3d bands by antiferromagnetic ordering of the high-spin S = 5/2 moments, MgIrO3 and ZnIrO3 have a gap in the Ir 5d bands under the influence of both spin-orbit coupling and electron correlation. Their electronic structures are similar to those in the spin-orbit coupled Mott insulators with the j eff = 1/2 pseudospin degree of freedom, as found in monoclinic A2IrO3 with A = Na and Li which have been studied as candidates for the Kitaev spin liquid. Indeed, we find that the effective exchange interactions between the j eff = 1/2 pseudospins are dominated by the Kitaev-type bond-dependent interaction and the symmetric off-diagonal interactions. On the other hand, for MnIrO3, we show that the local lattice structure is largely deformed, and both Mn 3d and Ir 5d bands appear near the Fermi level in a complicated manner, which makes the electronic and magnetic properties qualitatively different from MgIrO3 and ZnIrO3. Our results indicate that the IrO6 honeycomb network in the ilmenites AIrO3 with A = Mg and Zn would offer a good platform for exotic magnetism by the spin-orbital entangled moments like the Kitaev spin liquid.

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Antiferromagnetic Kitaev interactions in polar spin-orbit Mott insulators

Cited by 21 publications

References 58 publications

Vortex creation and control in the Kitaev spin liquid by local bond modulations

Vortex creation and control in the Kitaev spin liquid by local bond modulations

Generic Field-Driven Phenomena in Kitaev Spin Liquids: Canted Magnetism and Proximate Spin Liquid Physics

Electronic and magnetic properties of iridium ilmenites $A$IrO$_3$ ($A=$ Mg, Zn, and Mn)

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