Quenching the Haldane Gap in Spin-1 Heisenberg Antiferromagnets

Wierschem, Keola; Sengupta, Pinaki

doi:10.1103/physrevlett.112.247203

Cited by 54 publications

(65 citation statements)

References 59 publications

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“…[1][2][3][4][5][6][7][8]) and are predicted to display vibrant phase diagrams arising from competing interactions and their interplay with singleion anisotropy. These diagrams encompass quantum critical points [1,2], nematic and supersolid states [5,9,10], as well as topologically interesting gapped and quantum paramagnetic phases [11][12][13][14]. By contrast, because of the difficulty in making real examples of these systems, experimental work in this area moves more slowly and several predictions remain untested.…”

Section: Introductionmentioning

confidence: 99%

Determining the anisotropy and exchange parameters of polycrystalline spin-1 magnets

Blackmore¹,

Brambleby²,

Lancaster³

et al. 2019

New J. Phys.

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Although low-dimensional S=1 antiferromagnets remain of great interest, difficulty in obtaining highquality single crystals of the newest materials hinders experimental research in this area. Polycrystalline samples are more readily produced, but there are inherent problems in extracting the magnetic properties of anisotropic systems from powder data. Following a discussion of the effect of powder-averaging on various measurement techniques, we present a methodology to overcome this issue using thermodynamic measurements. In particular we focus on whether it is possible to characterise the magnetic properties of polycrystalline, anisotropic samples using readily available laboratory equipment. We test the efficacy of our method using the magnets [Ni(H 2 O) 2 (3,5-lutidine) 4 ](BF 4 ) 2 and Ni(H 2 O) 2 (acetate) 2 (4-picoline) 2 , which have negligible exchange interactions, as well as the antiferromagnet [Ni(H 2 O) 2 (pyrazine) 2 ](BF 4 ) 2 , and show that we are able to extract the anisotropy parameters in each case. The results obtained from the thermodynamic measurements are checked against electron-spin resonance and neutron diffraction. We also present a density functional method, which incorporates spin-orbit coupling to estimate the size of the anisotropy in [Ni(H 2 O) 2 (pyrazine) 2 ](BF 4 ) 2 .

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Section: Introductionmentioning

confidence: 99%

Determining the anisotropy and exchange parameters of polycrystalline spin-1 magnets

Blackmore¹,

Brambleby²,

Lancaster³

et al. 2019

New J. Phys.

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show abstract

“…Fortunately, the phase diagram of Hamiltonian (1) is well known numerically, 36,49,50 and shown in Fig. 5.…”

Section: B Approaching Criticalitymentioning

confidence: 99%

Dynamics of a bond-disorderedS=1quantum magnet nearz=1criticality

et al. 2015

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Neutron scattering is used to study NiCl2−2xBr2x·4SC(NH2)2, x = 0.06, a bond-disordered modification of the well-known gapped S = 1 antiferromagnetic quantum spin system NiCl2·4SC(NH2)2. The magnetic excitation spectrum throughout the Brillouin zone is mapped out at T = 60 mK using high-resolution time-of-flight spectroscopy. It is found that the dispersion of spin excitation is renormalized, as compared to that in the parent compound. The lifetime of excitations near the bottom of the band is substantially decreased. No localized states are found below the gap energy ∆ 0.2 meV. At the same time, localized zero wave vector states are detected above the top of the band. The results are consistent with a more or less continuous random distribution of bond strengths, and a discrete, possibly bimodal, distribution of single-ion anisotropies in the disordered material.

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“…In interpolating from decoupled spin chains to the square spin lattice (see Fig.1 with J = 1, J = 0, and J varying from 0 to 1 ) the behavior of the antiferromagnetic (AF) Heisenberg model depends strongly on the spin value. The critical feature of the spin-1/2 chain ground state makes the system susceptible to breaking the SU (2) symmetry with an infinitesimal interchain coupling J /J and develops long range Néel order; however for the spin-1 case 6 , it takes a very small value (J /J) c ∼ 0.0436, notably one order of magnitude smaller than the spin chain gap, to quench the Haldane phase and, simultaneously, to develop long range Néel order 7 .…”

Section: Introductionmentioning

confidence: 99%

One dimensionalization in the spin-1 Heisenberg model on the anisotropic triangular lattice

et al. 2017

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We investigate the effect of dimensional crossover in the ground state of the antiferromagnetic spin-1 Heisenberg model on the anisotropic triangular lattice that interpolates between the regime of weakly coupled Haldane chains (J J) and the isotropic triangular lattice (J = J). We use the density-matrix renormalization group (DMRG) and Schwinger boson theory performed at the Gaussian correction level above the saddle-point solution. Our DMRG results show an abrupt transition between decoupled spin chains and the spirally ordered regime at (J /J)c ∼ 0.42, signaled by the sudden closing of the spin gap. Coming from the magnetically ordered side, the computation of the spin stiffness within Schwinger boson theory predicts the instability of the spiral magnetic order toward a magnetically disordered phase with one-dimensional features at (J /J)c ∼ 0.43. The agreement of these complementary methods, along with the strong difference found between the intra-and the interchain DMRG short spin-spin correlations; for sufficiently large values of the interchain coupling, suggests that the interplay between the quantum fluctuations and the dimensional crossover effects gives rise to the one-dimensionalization phenomenon in this frustrated spin-1 Hamiltonian.

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Quenching the Haldane Gap in Spin-1 Heisenberg Antiferromagnets

Cited by 54 publications

References 59 publications

Determining the anisotropy and exchange parameters of polycrystalline spin-1 magnets

Determining the anisotropy and exchange parameters of polycrystalline spin-1 magnets

Dynamics of a bond-disorderedS=1quantum magnet nearz=1criticality

One dimensionalization in the spin-1 Heisenberg model on the anisotropic triangular lattice

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