Hole propagation in the Kitaev-Heisenberg model: From quasiparticles in quantum Néel states to non-Fermi liquid in the Kitaev phase

Trousselet, Fabien; Horsch, Peter; Oleś, Andrzej M.; You, Wen-Long

doi:10.1103/physrevb.90.024404

Cited by 22 publications

(37 citation statements)

References 86 publications

(97 reference statements)

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“…Characteristic examples include the Fermi Hubbard and t − J models [2][3][4][5], the Kitaev-Heisenberg model [6], as well as vacancy motion in solid 3 He crystals [7][8][9]. In quantum computing and information processing, relevant problems and algorithms are also frequently formulated as quantum walks on a network [10][11][12].…”

Section: A)mentioning

confidence: 99%

Quantum Walk in Degenerate Spin Environments

2016

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We study the propagation of a hole in degenerate (paramagnetic) spin environments. This canonical problem has important connections to a number of physical systems, and is perfectly suited for experimental realization with ultra-cold atoms in an optical lattice. At the short-to-intermediate timescale that we can access using a stochastic-series-type numeric scheme, the propagation turns out to be distinctly non-diffusive with the probability distribution featuring minima in both space and time due to quantum interference, yet the motion is not ballistic, except at the beginning. We discuss possible scenarios for long-term evolution that could be explored with an unprecedented degree of detail in experiments with single-atom resolved imaging.

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Section: A)mentioning

confidence: 99%

Quantum Walk in Degenerate Spin Environments

2016

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“…Second, a single hole in the Kitaev honeycomb model has been studied in Ref. 23 via exact diagonalization of small systems.…”

Section: Introductionmentioning

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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“…Above the percolation threshold where long-range order is absent, the fractionalized excitations dominate the spectrum and the low-temperature region may effectively be a dilute QSL. The robust nature of such QSL physics in RuCl 3 with respect to chemical substitution strongly motivates further investigation of dopants, in particular those that would introduce mobile charge carriers, an avenue which is predicted to bring about exotic superconductivity [41][42][43][44][45][46][47]. …”

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confidence: 99%

“…The motivation is two-fold: to understand the role of defects in Kitaevcandidate materials and to explore avenues towards suppression of long-range order. Numerous theoretical studies predict the emergence of novel superconductivity with hole doping in the strong Kitaev limit [41][42][43][44][45][46][47] [59,60]. Isoelectronic substitution within the solid solution (Na,Li) 2 IrO 3 decreased the magnetic ordering temperature, although phase separation has hampered efforts to completely suppress long-range order [61][62][63].…”

mentioning

confidence: 99%

“…The motivation is two-fold: to understand the role of defects in Kitaevcandidate materials and to explore avenues towards suppression of long-range order. Numerous theoretical studies predict the emergence of novel superconductivity with hole doping in the strong Kitaev limit [41][42][43][44][45][46][47] while bond disorder [48], dislocations [49], magnetic impurities [50], and spin vacancies [51][52][53][54][55][56][57][58] have also received theoretical attention. Experimentally, substitution of both magnetic and non-magnetic cations for Ir rapidly led to spin glass freezing in Na 2 IrO 3 and Li 2 IrO 3 [59,60].…”

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confidence: 99%

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Destabilization of Magnetic Order in a Dilute Kitaev Spin Liquid Candidate

et al. 2017

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The insulating honeycomb magnet α-RuCl3 exhibits fractionalized excitiations that signal its proximity to a Kitaev quantum spin liquid (QSL) state, however, at T = 0, fragile long-range magnetic order arises from non-Kitaev terms in the Hamiltonian. Spin vacancies in the form of Ir 3+ substituted for Ru are found to destabilize this long-range order. Neutron diffraction and bulk characterization of Ru1−xIrxCl3 show that the magnetic ordering temperature is suppressed with increasing x and evidence of zizag magnetic order is absent for x > 0.3. Inelastic neutron scattering demonstrates that the signature of fractionalized excitations is maintained over the full range of x investigated. The depleted lattice without magnetic order thus hosts a spin-liquid-like ground state that may indicate the relevance of Kitaev physics in the magnetically dilute limit of RuCl3.PACS numbers: 75.30. Kz, 75.10.Kt The quantum spin liquid (QSL) holds particular fascination as a state of matter that exhibits strong quantum entanglement yet is devoid of long-range order [1, 2]. These exotic states can possess topologically protected fractionalized excitations, with possible implications for quantum information science [3, 4]. A prototypcal example is the Kitaev model on a honeycomb lattice [5], which can be solved exactly and has a QSL ground state. An effective Hamiltonian with Kitaev terms consisting of bond-directional Ising couplings may arise in spin-orbit assisted Mott insulators with J ef f = 1/2 moments in an edge-sharing octahedral environment [6]. A strong push for the experimental realization of quasi-2D honeycomb lattices showing Kitaev physics initially focused on iridate materials with the chemical formula A 2 IrO 3 [7][8][9][10], and more recently α-RuCl 3 [11][12][13][14]. Each of these compounds orders magnetically at low temperatures in a zigzag or incommensurate phase [15][16][17][18][19][20][21], and the effective low energy Hamiltonian is believed to be described by a generalized Heisenberg-Kitaev-Γ model [22][23][24][25][26][27][28][29][30][31][32][33]. Despite the appearance of long-range order, broad scattering continua observed via inelastic neutron or Raman scattering in α-RuCl 3 [13,[34][35][36] and the iridates [37] match the predicted signatures of itinerant Majorana fermions in pure Kitaev calculations [38][39][40], suggesting that these materials are proximate to the QSL state and that Kitaev interactions play an important role.In this letter, we report the evolution of the magnetic ground state in α-RuCl 3 with magnetic Ru 3+ substituted by nonmagnetic Ir 3+ , and determine a phase diagram as a function of temperature and dilution. The motivation is two-fold: to understand the role of defects in Kitaevcandidate materials and to explore avenues towards suppression of long-range order. Numerous theoretical studies predict the emergence of novel superconductivity with hole doping in the strong Kitaev limit [41][42][43][44][45][46][47] [59,60]. Isoelectronic substitution within the solid solution (Na,Li) ...

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Hole propagation in the Kitaev-Heisenberg model: From quasiparticles in quantum Néel states to non-Fermi liquid in the Kitaev phase

Cited by 22 publications

References 86 publications

Quantum Walk in Degenerate Spin Environments

Quantum Walk in Degenerate Spin Environments

Coherent hole propagation in an exactly solvable gapless spin liquid

Destabilization of Magnetic Order in a Dilute Kitaev Spin Liquid Candidate

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