Optical probe of Heisenberg-Kitaev magnetism in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>α</mml:mi><mml:mtext>−</mml:mtext><mml:msub><mml:mi>RuCl</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Sandilands, Luke J.; Sohn, Chae Hoon; Park, Hyun Ju; Kim, So Yeun; Kim, Kyung Wan; Sears, Jennifer; Kim, Yong Baek; Noh, Tae Won

doi:10.1103/physrevb.94.195156

Cited by 53 publications

(61 citation statements)

References 55 publications

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“…Under ambient pressure, α-RuCl 3 is considered as a spin-orbit assisted j e f f = 1/2 Mott insulator with a Mott gap of about 1.1 eV [66][67][68][69][70]. Specific heat measurements [71] show a pressure sensitivity of the Néel transition and indicate a suppression of the magnetic order at around 0.7 GPa (in accordance with the theoretical, predicted coupling constants [60]).…”

Section: α-Ruclsupporting

confidence: 76%

Pressure-Tuned Interactions in Frustrated Magnets: Pathway to Quantum Spin Liquids?

Biesner

Uykur

2019

Crystals

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Quantum spin liquids are prime examples of strongly entangled phases of matter with unconventional exotic excitations. Here, strong quantum fluctuations prohibit the freezing of the spin system. On the other hand, frustrated magnets, the proper platforms to search for the quantum spin liquid candidates, still show a magnetic ground state in most of the cases. Pressure is an effective tuning parameter of structural properties and electronic correlations. Nevertheless, the ability to influence the magnetic phases should not be forgotten. We review experimental progress in the field of pressure-tuned magnetic interactions in candidate systems. Elaborating on the possibility of tuned quantum phase transitions, we further show that chemical or external pressure is a suitable parameter in these exotic states of matter.

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Section: α-Ruclsupporting

confidence: 76%

Pressure-Tuned Interactions in Frustrated Magnets: Pathway to Quantum Spin Liquids?

Biesner

Uykur

2019

Crystals

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“…Single crystals of α-RuCl 3 were prepared using high-temperature vapor-transport techniques from pure α-RuCl 3 powder with no additional transport agent. Crystals grown by an identical method have been extensively characterized via bulk and neutron scattering techniques39,42,63 revealing behavior consistent with what is expected for a relativistic Mott insulator with a large Kitaev interaction16,24,25,29,30,32,33,41,43,45,65,67,68 . The crystals have been shown to consistently exhibit a single dominant magnetic phase at low tempera-…”

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confidence: 58%

The range of non-Kitaev terms and fractional particles in α-RuCl3

Wang

Osterhoudt

Tian³

et al. 2020

npj Quantum Mater.

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Significant efforts have focused on the magnetic excitations of relativistic Mott insulators, predicted to realize the Kitaev quantum spin liquid (QSL). This exactly solvable model involves a highly entangled state resulting from bond-dependent Ising interactions that pro-1 arXiv:2003.09274v1 [cond-mat.str-el] 18 Mar 2020 duce excitations which are non-local in terms of spin flips. A key challenge in real materials is identifying the relative size of the non-Kitaev terms and their role in the emergence or suppression of fractional excitations. Here, we identify the energy and temperature boundaries of non-Kitaev interactions by direct comparison of the Raman susceptibility of α-RuCl 3 with quantum Monte Carlo (QMC) results for the Kitaev QSLs. Moreover, we further confirm the fractional nature of the magnetic excitations, which is given by creating a pair of fermionic quasiparticles. Interestingly, this fermionic response remains valid in the non-Kitaev range. Our results and focus on the use of the Raman susceptibility provide a stringent new test for future theoretical and experimental studies of QSLs. Exotic excitations with fractional quantum numbers are a key characteristic of QSLs 1-4 , which result from the long range entanglement of these non-trivial topological phases 5-7 . Originating from frustrated magnetic interactions, the fractional nature inspires an overarching goal of studying QSLs, realizing topological quantum computing immune to decoherence, with high operating temperatures from large exchange interactions 8, 9 . The last decade has seen great progress towards identifying the fractional excitations of QSLs 10-18 . Attention has focused on relativistic Mott insulators that are close to the exactly solvable Kitaev model with a QSL ground state. In materials such as A 2 IrO 3 (A = Cu, Li or Na) 4, 8, 19-23 and α-RuCl 3 24-27 , the large spin-orbit coupling and Coulomb repulsion result in j ef f = 1/2 moments on a honeycomb lattice 2, 9, 28-35 .According to the pure Kiteav model, in these materials spin flips could produce Z 2 gauge fluxes and dispersive Majorana fermions. 14, 36 .

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“…The increase of σ 1 (ω) above 0.9 eV indicates the Mott gap. Above 1 eV, σ 1 (ω) reaches about 10 3 ( cm) −1 [38,41]. The much smaller values of σ 1 (ω) below the gap are typical for weak phonon-assisted or higher-order absorption features [53].…”

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confidence: 98%

“…Furthermore, several groups reported on infrared absorption bands at 0.30, 0.53, and 0.75 eV [4,[30][31][32][33][34][35]. The 0.30 eV peak was assigned to the Mott gap [4,33,34], but a gap of about 1 eV is well established by different techniques [30][31][32][36][37][38][39][40][41]. Thus far, there is no convincing explanation for this multitude of excitations below the gap.…”

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confidence: 99%

Multiple spin-orbit excitons and the electronic structure of α−RuCl3

Warzanowski

Borgwardt

Hopfer

et al. 2020

Phys. Rev. Research

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The honeycomb compound α-RuCl 3 is widely discussed as a proximate Kitaev spin-liquid material. This scenario builds on spin-orbit entangled j = 1/2 moments arising for a t 5 2g electron configuration with strong spin-orbit coupling λ and a large cubic crystal field. The actual low-energy electronic structure of α-RuCl 3 , however, is still puzzling. In particular, infrared absorption features at 0.30, 0.53, and 0.75 eV seem to be at odds with a j = 1/2 scenario. Also the energy of the spin-orbit exciton, the excitation from j = 1/2 to 3/2, and thus the value of λ, are controversial. Combining infrared and Raman data, we show that the infrared features can be attributed to single, double, and triple spin-orbit excitons. We find λ = 0.16 eV and = 42(4) meV for the observed noncubic crystal-field splitting, supporting the validity of the j = 1/2 picture for α-RuCl 3. The unusual strength of the double excitation is related to the underlying hopping interactions, which form the basis for dominant Kitaev exchange.

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Optical probe of Heisenberg-Kitaev magnetism inα−RuCl3

Cited by 53 publications

References 55 publications

Pressure-Tuned Interactions in Frustrated Magnets: Pathway to Quantum Spin Liquids?

Pressure-Tuned Interactions in Frustrated Magnets: Pathway to Quantum Spin Liquids?

The range of non-Kitaev terms and fractional particles in α-RuCl3

Multiple spin-orbit excitons and the electronic structure of α−RuCl3

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