A gapless charge mode induced by the boundary states in the half-filled Hubbard open chain

Deguchi, Tetsuo; Yue, Rui-Hong; Kusakabe, Koichi

doi:10.1088/0305-4470/31/36/006

Cited by 9 publications

(11 citation statements)

References 17 publications

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“…32 The Bethe-ansatz solutions for OBC suggest that an analogous crossover from an IM with real k eff to a BM with a damping nature can be found as a continuous change from a real to an imaginary rapidity. 33 …”

Section: Application To S = 2 Heisenberg Chain and Conclusionmentioning

confidence: 99%

Determination of boundary scattering, magnon-magnon scattering, and the Haldane gap in Heisenberg spin chains

Ueda

Kusakabe

2011

Phys. Rev. B

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The antiferromagnetic spin-one chain is considerably one of the most fundamental quantum many-body systems, with symmetry protected topological order in the ground state. Here, we present results for its dynamical spin structure factor at finite temperatures, based on a combination of exact numerical diagonalization, matrix-product-state calculations and quantum Monte Carlo simulations. Open finite chains exhibit a sub-gap band in the thermal spectral functions, indicative of localized edge-states. Moreover, we observe the thermal activation of a distinct low-energy continuum contribution to the spin spectral function with an enhanced spectral weight at low momenta and its upper threshold. This emerging thermal spectral feature of the Haldane spin-one chain is shown to result from intra-band magnon scattering due to the thermal population of the single-magnon branch, which features a large bandwidth-to-gap ratio. These findings are discussed with respect to possible future studies on spin-one chain compounds based on inelastic neutron scattering. PACS numbers: 75.10.Jm, 75.40.Cx, 75.40.Mg One-dimensional quantum spin models constitute basic condensed matter many-body systems that despite their simplicity exhibit a rich variety of emergent phenomena [1]. These include the formation of collective excitations and non-classical ground states with characteristic patterns in the quantum entanglement. From this perspective, Haldane's conjecture [2-4] on a fundamental difference in the low-energy physics of integer-valued spin chains with respect to the spin-half Heisenberg chain has established the spin-one chain model as a fundamental spin system, which furthermore finds realizations in various, mainly Ni 2+-based compounds [5-17]. Its properties have been intensively explored in both theoretical and numerical, as well as experimental studies in recent years, mainly with a focus toward the peculiar properties of the gapped ground state [18, 19], which is now understood as a most basic instance of symmetry protected topological (SPT) order [20, 21]. This leads, e.g., to the formation of a pair of entangled spin-half low-energy edge states for open finite chains [22]. Dynamical probes of quantum magnetism in spin-one chain compounds, performed using inelastic neutron scattering, have confirmed the gapped magnetic excitation spectrum [6, 15, 23-27]. At low temperatures , the corresponding dynamical spin structure factor is dominated by the gapped single-magnon branch, with additional contributions from multi-magnon continuum states, leading to the termination of the single-magnon branch due to decay and scattering with the two-magnon continuum states [28-46], cf. Fig. 1 for an illustration. The effects of thermal fluctuations on the dynamical spin structure factor at elevated temperatures [15, 47, 48] have been less intensively investigated theoretically, in partic-0 π/4 π/2 3π/4 π q 0.0 0.5 1.0 1.5 2.0 2.5 ω/J two magnon continuum three magnon continuum thermal intra-band magnon scattering edge-state mode FIG. 1. Sketch...

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Section: Application To S = 2 Heisenberg Chain and Conclusionmentioning

confidence: 99%

Determination of boundary scattering, magnon-magnon scattering, and the Haldane gap in Heisenberg spin chains

Ueda

Kusakabe

2011

Phys. Rev. B

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“…There are existing theoretical approaches that employ the Bethe ansatz method, and the closing of the Mott gap has been discussed [3,4]. In these studies, however, electric fields are not actually applied, but the left-going and right-going hopping terms are made different instead.…”

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confidence: 99%

Breakdown of a Mott Insulator: A Nonadiabatic Tunneling Mechanism

2003

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Time-dependent nonequilibrium properties of a strongly correlated electron system driven by large electric fields is obtained by means of solving the time-dependent Schrödinger equation for the many-body wave function numerically in one dimension. While the insulator-to-metal transition depends on the electric field and the interaction, the metallization is found to be described in terms of a universal Landau-Zener quantum tunneling among the many-body levels. These processes induce current oscillation for small systems, while giving rise to finite resistivity through dissipation for larger systems/on longer time scales.

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“…The value of the quantity w 2 for p = p 3c is in general different from the values corresponding to the mentioned two points for larger values of u when correlations of fluctuations of the number of electrons with spin up and with spin down is nonzero. For a finite chain with L finite we have for p > p 3c a hole at the boundary site 1, and for p < p 3c there is an electron at this boundary site 1 [7]. As we can see there is no phase transition in the thermodynamic limit.…”

Section: Introductionmentioning

confidence: 67%

“…Let us now concentrate on the charge sector. In [7] the Hubbard model is discussed for the ground state and some excited states of the half-filled case for an open chain with L sites. Only one of the boundary sites has a different value of chemical potential in this case.…”

Section: Introductionmentioning

confidence: 99%

“…Only one of the boundary sites has a different value of chemical potential in this case. Authors [7] considered the case when the boundary site has a negative chemical potential -p and the Hubbard coupling U is positive. They have shown by an analytic method that when p is larger than the transfer integral some of the ground-state solutions of the Bethe ansatz equations become complex-valued.…”

Section: Introductionmentioning

confidence: 99%

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Quantum critical phenomena, entanglement entropy and Hubbard model in 1d with the boundary site with a negative chemical potential −p and the Hubbard coupling U positive

Hudák

2009

Physics Letters A

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Recently the ground state and some excited states of the half-filled case of the 1d Hubbard model were discussed for an open chain with L sites. Authors considered the case when the boundary site has a negative chemical potential -p and the Hubbard coupling U is positive. They have shown by an analytic method that when p is larger than the transfer integral some of the ground-state solutions of the Bethe ansatz equations become complex-valued. They have found that there is a surface phase transition at some critical value p c ; when p < p c all the charge excitations have the gap for this case, while there exists a massless charge mode when p > p c . To find whether this "surface phase transition" is of the first order or of the second order we have used the entanglement entropy concept. The entropy and its derivative has a discontinuity there, so this transition is of the first order.2

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A gapless charge mode induced by the boundary states in the half-filled Hubbard open chain

Cited by 9 publications

References 17 publications

Determination of boundary scattering, magnon-magnon scattering, and the Haldane gap in Heisenberg spin chains

Determination of boundary scattering, magnon-magnon scattering, and the Haldane gap in Heisenberg spin chains

Breakdown of a Mott Insulator: A Nonadiabatic Tunneling Mechanism

Quantum critical phenomena, entanglement entropy and Hubbard model in 1d with the boundary site with a negative chemical potential −p and the Hubbard coupling U positive

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