Quantum phases of hardcore bosons with long-range interactions on a square lattice

Yamamoto, Daisuke; Masaki, Akiko; Danshita, Ippei

doi:10.1103/physrevb.86.054516

Cited by 72 publications

(124 citation statements)

References 67 publications

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“…One promising approach to address the problem is the CMF+S method [25,29,37,40]. This method has been applied to the triangular-lattice XXZ model (1) for S = 1/2 and has successfully produced the ground-state phase diagram including the transition between the 0-coplanar and π-coplanar phases [29].…”

Section: Cluster Mean-field Theory With Cluster-size Scaling Formentioning

confidence: 99%

“…11), N µ is the number of total sites belonging to the sublattice µ in the M C clusters, and β = 1/T (we take T → 0 to consider the ground-state properties). Substituting m [25,29,37,40]. Note that a similar approach has been also applied to study an S = 1 bilinear-biquadratic model with single-ion anisotropy (at zero magnetic field) [41].…”

Section: Cluster Mean-field Theory With Cluster-size Scaling Formentioning

confidence: 99%

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Exact diagonalization and cluster mean-field study of triangular-lattice XXZ antiferromagnets near saturation

et al. 2017

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Quantum magnetic phases near the magnetic saturation of triangular-lattice antiferromagnets with XXZ anisotropy have been attracting renewed interest since it has been suggested that a nontrivial coplanar phase, called the π-coplanar or Ψ phase, could be stabilized by quantum effects in a certain range of anisotropy parameter J/Jz besides the well-known 0-coplanar (known also as V ) and umbrella phases. Recently, Sellmann et al. [Phys. Rev. B 91, 081104(R) (2015)] claimed that the π-coplanar phase is absent for S = 1/2 from an exact-diagonalization analysis in the sector of the Hilbert space with only three down-spins (three magnons). We first reconsider and improve this analysis by taking into account several low-lying eigenvalues and the associated eigenstates as a function of J/Jz and by sensibly increasing the system sizes (up to 1296 spins). A careful identification analysis shows that the lowest eigenstate is a chirally antisymmetric combination of finite-size umbrella states for J/Jz 2.218 while it corresponds to a coplanar phase for J/Jz 2.218. However, we demonstrate that the distinction between 0-coplanar and π-coplanar phases in the latter region is fundamentally impossible from the symmetry-preserving finite-size calculations with fixed magnon number. Therefore, we also perform a cluster mean-field plus scaling analysis for small spins S ≤ 3/2. The obtained results, together with the previous large-S analysis, indicate that the π-coplanar phase exists for any S except for the classical limit (S → ∞) and the existence range in J/Jz is largest in the most quantum case of S = 1/2.

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Section: Cluster Mean-field Theory With Cluster-size Scaling Formentioning

confidence: 99%

Section: Cluster Mean-field Theory With Cluster-size Scaling Formentioning

confidence: 99%

Exact diagonalization and cluster mean-field study of triangular-lattice XXZ antiferromagnets near saturation

et al. 2017

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“…(5), based on the mean-field free energy Eq. (10). The dashed line is the separatrix between "ferromagnetic" and "antiferromagentic" Z 2 -ordering in the Isingpseudospin-sector.…”

Section: Resultsmentioning

confidence: 99%

“…We do this by carrying out single-site and cluster mean-field calculations, 9,10 and compare them to results of largescale Monte-Carlo simulations, going well beyond what has previously been obtained in the literature. 11,12 In so doing, we identify a source of strong fluctuation effects other than low dimensionality, namely frustration in the phases of the superconducting order parameters due to interband Josephson couplings.…”

Section: Introductionmentioning

confidence: 99%

Fluctuation Effects in Phase-Frustrated Multiband Superconductors

Bojesen

Sudbø

2015

J Supercond Nov Magn

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We compare the phase-diagrams of an effective theory of a three-dimensional multi-band superconductor obtained within standard and cluster mean-field theories, and in large-scale Monte Carlo simulations. In three dimensions, mean field theory fails in locating correctly the positions of the phase transitions, as well as the character of the transitions between the different states. A cluster mean-field calculations taking into account order-parameter fluctuations in a local environment improves the results considerably for the case of extreme type-II superconductors where gauge-field fluctuations are negligible. The large fluctuations in the multi-component superconducting order parameter originate with strong frustration due to interband Josephson-couplings. A novel chiral metallic phase found in previous works using large scale Monte-Carlo computations, is not obtained either within the single-site mean-field theory or the improved cluster mean-field theory of order parameter fluctuations. In three-dimensional superconductors, this unusual metallic phase originates with gauge-field fluctuations.

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“…Although the Gutzwiller method has common restrictions of the mean-field methods, it has provided versatile applications in qualitative calculations of both stationary states and time-evolution dynamics. In recent, cluster bosonic Gutzwiller methods [29][30][31][32][33][34] have been developed by coupling multi-site clusters rather than single sites with the mean field. By employing the cluster Gutzwiller method, some properties of many-body LZ phenomena in repulsive BHL [35] and some quantum phases in attractive BHL [36] have been explored.…”

Section: Introductionmentioning

confidence: 99%

Cluster Gutzwiller study of the Bose-Hubbard ladder: Ground-state phase diagram and many-body Landau-Zener dynamics

et al. 2015

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We present a cluster Gutzwiller mean-field study for ground states and time-evolution dynamics in the Bose-Hubbard ladder (BHL), which can be realized by loading Bose atoms in double-well optical lattices. In our cluster mean-field approach, we treat each double-well unit of two lattice sites as a coherent whole for composing the cluster Gutzwiller ansatz, which may remain some residual correlations in each two-site unit. For a unbiased BHL, in addition to conventional superfluid phase and integer Mott insulator phases, we find that there are exotic fractional insulator phases if the inter-chain tunneling is much stronger than the intra-chain one. The fractional insulator phases can not be found by using a conventional mean-field treatment based upon the single-site Gutzwiller ansatz. For a biased BHL, we find there appear single-atom tunneling and interaction blockade if the system is dominated by the interplay between the on-site interaction and the inter-chain bias. In the many-body Landau-Zener process, in which the inter-chain bias is linearly swept from negative to positive or vice versa, our numerical results are qualitatively consistent with the experimental observation [Nat. Phys. 7, 61 (2011)]. Our cluster bosonic Gutzwiller treatment is of promising perspectives in exploring exotic quantum phases and time-evolution dynamics of bosonic particles in superlattices.

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Quantum phases of hardcore bosons with long-range interactions on a square lattice

Cited by 72 publications

References 67 publications

Exact diagonalization and cluster mean-field study of triangular-lattice XXZ antiferromagnets near saturation

Exact diagonalization and cluster mean-field study of triangular-lattice XXZ antiferromagnets near saturation

Fluctuation Effects in Phase-Frustrated Multiband Superconductors

Cluster Gutzwiller study of the Bose-Hubbard ladder: Ground-state phase diagram and many-body Landau-Zener dynamics

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