Low-Energy Spin Dynamics of the Honeycomb Spin Liquid Beyond the Kitaev Limit

Song, Xueyang; You, Yi-Zhuang; Balents, Leon

doi:10.1103/physrevlett.117.037209

Cited by 119 publications

(116 citation statements)

References 34 publications

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“…The low-energy physics is still captured by a single mode of (dressed) Dirac fermions, but any local disturbance must be represented by a sum of all local fermion terms allowed by symmetry. 30 In this case, the disturbance due to the hole might not couple to a set of non-degenerate levels (see Secs. III and IV), and therefore the orthogonality catastrophe might not be governed by a single (vanishing) phase shift at the Fermi energy.…”

Section: Discussionmentioning

confidence: 99%

Coherent hole propagation in an exactly solvable gapless spin liquid

Halász

Chalker

2016

Phys. Rev. B

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We examine the dynamics of a single hole in the gapless phase of the Kitaev honeycomb model, focusing on the slow-hole regime where the bare hopping amplitude t is much less than the Kitaev exchange energy J. In this regime, the hole does not generate gapped flux excitations and is dressed only by the gapless fermion excitations. Investigating the single-hole spectral function, we find that the hole propagates coherently with a quasiparticle weight that is finite but approaches zero as t/J → 0. This conclusion follows from two approximate treatments, which capture the same physics in complementary ways. Both treatments use the stationary limit as an exactly solvable starting point to study the spectral function approximately (i) by employing a variational approach in terms of a trial state that interpolates between the limits of a stationary hole and an infinitely fast hole and (ii) by considering a special point in the gapless phase that corresponds to a simplified one-dimensional problem.

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Section: Discussionmentioning

confidence: 99%

Coherent hole propagation in an exactly solvable gapless spin liquid

Halász

Chalker

2016

Phys. Rev. B

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“…The slowing-down of spin fluctuations might then dominate the low-temperature magnetic properties [42,43]. The power-law dependence of 1/T 1 can be compared with that found in the SOC-driven 5d spin-liquid compound Na 4 Ir 3 O 8 [47] and other low-dimensional QMs [18,19,63,68,69], which is attributed to the existence of a gapless state in the spin excitation spectrum and is in accord with the finite value of χ and K, and C m ∼ T 2 behavior at low T . The longitudinal nuclear spin-lattice relaxation rate is given by the low-energy (ω) and momentum-space (q) integrated hyperfine form factor A(q,ω) and the imaginary part of the complex dynamic electron susceptibility χ (q,ω) [proportional to S(q,ω), the dynamic structure factor].…”

Section: Resultsmentioning

confidence: 99%

Local magnetism and spin dynamics of the frustrated honeycomb rhodate Li2RhO3

et al. 2017

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“…(1). In general, the high-energy response is robust against such perturbations, even beyond the phase transition into an ordered phase [26], but the low-energy response of a generic KSL can be completely different from that of a pure Kitaev model [58]. Nevertheless, we expect that the lowenergy features of each SC RIXS response in Fig.…”

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confidence: 95%

Probing Spinon Nodal Structures in Three-Dimensional Kitaev Spin Liquids

2017

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We propose that resonant inelastic X-ray scattering (RIXS) is an effective probe of the fractionalized excitations in three-dimensional (3D) Kitaev spin liquids. While the non-spin-conserving RIXS responses are dominated by the gauge-flux excitations and reproduce the inelastic-neutron-scattering response, the spin-conserving (SC) RIXS response picks up the Majorana-fermion excitations and detects whether they are gapless at Weyl points, nodal lines, or Fermi surfaces. As a signature of symmetry fractionalization, the SC RIXS response is suppressed around the Γ point. On a technical level, we calculate the exact SC RIXS responses of the Kitaev models on the hyperhoneycomb, stripyhoneycomb, hyperhexagon, and hyperoctagon lattices, arguing that our main results also apply to generic 3D Kitaev spin liquids beyond these exactly solvable models.Quantum spin liquids (QSLs) are exotic and entirely quantum phases of matter [1,2] From a theoretical point of view, KSLs are particularly appealing because each of them has an exactly solvable limit governed by a Kitaev model [3]. In general, the Kitaev model is defined on a tricoordinated lattice with S = 1/2 spins σ x,y,z r at the sites r, which are coupled to their neighbors via bonddependent Ising interactions. The Hamiltonian readswhere J x,y,z are the coupling constants for the three types of bonds x, y, and z. Remarkably, this model is exactly solvable whenever there is precisely one bond of each type around each site of the tricoordinated lattice.These exactly solvable Kitaev models have been defined on a wide range of tricoordinated 3D lattices [4][5][6][7][8], including the hyperhoneycomb, stripyhoneycomb, hyperhexagon, and hyperoctagon lattices (see Fig. 1). In the experimentally relevant isotropic regime (J x ≈ J y ≈ J z ), the ground state is a gapless Z 2 QSL, while the (fractionalized) excitations are gapless Majorana fermions and gapped Z 2 gauge fluxes. Importantly, the Majorana fermions (spinons) exhibit a rich variety of nodal structures due to the different (projective) ways symmetries can act on them [5][6][7]. Indeed, they are gapless along nodal lines for the hyperhoneycomb and the stripyhoneycomb models [4], on Fermi surfaces for the hyperoctagon model [5], and at Weyl points for the hyperhexagon model [7].From an experimental point of view, however, it is difficult to identify and characterize QSLs due to the lack of any local order parameters that could be used as "smoking-gun" signatures. In recent years, a remarkable theoretical and experimental progress has been achieved in understanding that fractionalization is one of the most promising hallmarks of a QSL. Indeed, it has been demonstrated that fractionalized excitations, which are Majorana fermions and Z 2 gauge fluxes for KSLs, can be probed by conventional spectroscopic techniques, such as inelastic neutron scattering (INS) [26,[31][32][33][34], Raman scattering with visible light [21,25,[35][36][37][38][39], and resonant inelastic X-ray scattering (RIXS) [40][41][42].In this Letter, we propo...

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Low-Energy Spin Dynamics of the Honeycomb Spin Liquid Beyond the Kitaev Limit

Cited by 119 publications

References 34 publications

Coherent hole propagation in an exactly solvable gapless spin liquid

Coherent hole propagation in an exactly solvable gapless spin liquid

Local magnetism and spin dynamics of the frustrated honeycomb rhodate Li2RhO3

Probing Spinon Nodal Structures in Three-Dimensional Kitaev Spin Liquids

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