Critical Level Crossings and Gapless Spin Liquid in the Square-Lattice Spin-
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Wang, Ling; Sandvik, Anders W.

doi:10.1103/physrevlett.121.107202

Cited by 167 publications

(154 citation statements)

References 66 publications

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“…Even then, higher singlets (apart from s,1 ) are not well below t . Consistent with previous works [11][12][13][14][15][16][17][18] level scheme indicates on a change of the g.s. character for J 2 > 0.6.…”

Section: Heisenberg Model With Ring Exchange On Triangular Latticesupporting

confidence: 90%

“…In order to get also excited (singlet) states within S z tot = 0 sector we evaluate the g.s. wave-function |ψ 0 and then construct effective Hamiltonian for the excited states 65], and then repeat the standard DMRG algorithm for H 1 . The requirement of orthogonality is, however, difficult to meet for excited states which are (due to o.b.c.)…”

Section: Methodsmentioning

confidence: 99%

“…character for J 2 > 0.6. As a consequence, the SL in the intermediate regime, and even more on the singlet-dominated regime is less conclusive, and other options [17,75] have to be also considered.…”

Section: Heisenberg Model With Ring Exchange On Triangular Latticementioning

confidence: 99%

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Vanishing Wilson ratio as the hallmark of quantum spin-liquid models

Prelovšek

Morita

Tohyama

et al. 2020

Phys. Rev. Research

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We present numerical results for finite-temperature T > 0 thermodynamic quantities, entropy s(T ), uniform susceptibility χ0(T ) and the Wilson ratio R(T ), for several isotropic S = 1/2 extended Heisenberg models which are prototype models for planar quantum spin liquids. We consider in this context the frustrated J1-J2 model on kagome, triangular, and square lattice, as well as the Heisenberg model on triangular lattice with the ring exchange. Our analysis reveals that typically in the spin-liquid parameter regimes the low-temperature s(T ) remains considerable, while χ0(T ) is reduced consistent mostly with a triplet gap. This leads to vanishing R(T → 0), being the indication of macroscopic number of singlets lying below triplet excitations. This is in contrast to J1-J2 Heisenberg chain, where R(T → 0) either remains finite in the gapless regime, or the singlet and triplet gap are equal in the dimerized regime. arXiv:1912.00876v1 [cond-mat.str-el]

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Section: Heisenberg Model With Ring Exchange On Triangular Latticesupporting

confidence: 90%

Section: Methodsmentioning

confidence: 99%

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Vanishing Wilson ratio as the hallmark of quantum spin-liquid models

Prelovšek

Morita

Tohyama

et al. 2020

Phys. Rev. Research

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“…The consensus is that indeed an intermediate quantum fluctuation driven phase emerges, and the estimated range for this quantum phase is 0.42J 2 /J 1 0.62. Numerical simulations indicate that this is a QSL, either a gaped [45,46], or a gapless  2 QSL [47], while, a more recent work, using renormalization group arguments, suggests instead that this phase is not a true QSL, but rather a so called plaquette valence-bond phase [48]. .…”

Section: Mott Insulating Phase Diagrammentioning

confidence: 94%

“…In the insulating phase the Hamiltonian on the form of (9) is part of a larger group of Hamiltonians that can be expressed asˆˆˆˆ( [45][46][47][48]. The consensus is that indeed an intermediate quantum fluctuation driven phase emerges, and the estimated range for this quantum phase is 0.42J 2 /J 1 0.62.…”

Section: Mott Insulating Phase Diagrammentioning

confidence: 99%

Magnetic phases of orbital bipartite optical lattices

Saugmann

Larson

2020

New J. Phys.

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In the Hamburg cold atom experiment with orbital states in an optical lattice, s-and p-orbital atomic states hybridize between neighboring sites. In this work we show how this alternation of sites hosting s-and p-orbital states gives rise to a plethora of different magnetic phases, quantum and classical. We focus on phases whose properties derive from frustration originating from a competition between nearest and next nearest neighboring exchange interactions. The physics of the Mott insulating phase with unit filling is described by an effective spin-1/2 Hamiltonian showing great similarities with the J 1 -J 2 model. Based on the knowledge of the J 1 -J 2 model, supported by numerical simulations, we discuss the possibility of a quantum spin liquid phase in the present optical lattice system. In the superfluid regime we consider the parameter regime where the s-orbital states can be adiabatically eliminated to give an effective model for the p-orbital atoms. At the mean-field level we derive a generalized classical XY model, and show that it may support maximum frustration. When quantum fluctuations can be disregarded, the ground state should be a spin glass. Figure 5. The energy of the ground state of the effective Hamiltonian for the Mott insulating phase (9). The energy is found for zero field h=0, and for = = J J J 0.9 X Y Z 1 1 1 , and as a function of J J Z Z 2 1 . The plot shows that an energy plateau is formed around = J J 0.5 Z Z 2 1 indicating the possibility that a there is an intermediate phase in between the Néel and striped phases.we see four distinct phases, the ferromagnetic phase (green), the Néel phase (white), the striped phase (dark pink), and the disordered phase (pink). In this (classical) limit all phase transitions are first first order. As we consider non-zero couplings = J J X Y 1 1 a fifth mean-field phase appears (light green/pink), this phase grows with increasing couplings = J J X Y 1 1 , and all PTs except for the one between the Néel phase and the ferromagnet phase, and the Néel and the new phase, appear to be second order. The new phase survives also for zero field, J Z =0, provided that = J J X Y 1 1 is large enough. At this mean-field level, the properties of the intermediate fifth phase is unknown. The dispersed dots are numerical errors for which the simulations are not capable of finding the true ground state.

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Anisotropic deconfined criticality in Dirac spin liquids

Shackleton

Sachdev

2022

J. High Energ. Phys.

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We analyze a Higgs transition from a U(1) Dirac spin liquid to a gapless ℤ2 spin liquid. This ℤ2 spin liquid is of relevance to the spin S = 1/2 square lattice antiferromagnet, where recent numerical studies have given evidence for such a phase existing in the regime of high frustration between nearest neighbor and next-nearest neighbor antiferromagnetic interactions (the J1-J2 model), appearing in a parameter regime between the vanishing of Néel order and the onset of valence bond solid ordering. The proximate Dirac spin liquid is unstable to monopole proliferation on the square lattice, ultimately leading to Néel or valence bond solid ordering. As such, we conjecture that this Higgs transition describes the critical theory separating the gapless ℤ2 spin liquid of the J1-J2 model from one of the two proximate ordered phases. The transition into the other ordered phase can be described in a unified manner via a transition into an unstable SU(2) spin liquid, which we have analyzed in prior work. By studying the deconfined critical theory separating the U(1) Dirac spin liquid from the gapless ℤ2 spin liquid in a 1/Nf expansion, with Nf proportional to the number of fermions, we find a stable fixed point with an anisotropic spinon dispersion and a dynamical critical exponent z ≠ 1. We analyze the consequences of this anisotropic dispersion by calculating the angular profiles of the equal-time Néel and valence bond solid correlation functions, and we find them to be distinct. We also note the influence of the anisotropy on the scaling dimension of monopoles.

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Critical Level Crossings and Gapless Spin Liquid in the Square-Lattice Spin- 1/2 J1−J

Cited by 167 publications

References 66 publications

Vanishing Wilson ratio as the hallmark of quantum spin-liquid models

Vanishing Wilson ratio as the hallmark of quantum spin-liquid models

Magnetic phases of orbital bipartite optical lattices

Anisotropic deconfined criticality in Dirac spin liquids

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