Shijie Hu - Profile on Academia.edu (original) (raw)

Papers by Shijie Hu

Research paper thumbnail of Unusual excitations and double-peak specific heat in a bond-alternating spin-1 K−Γ chain

Physical Review Research, 2021

Research paper thumbnail of Dirac Spin Liquid on the Spin- 1/2 Triangular Heisenberg Antiferromagnet

Physical Review Letters, 2019

We study the spin liquid candidate of the spin-1/2 J1-J2 Heisenberg antiferromagnet on the triang... more We study the spin liquid candidate of the spin-1/2 J1-J2 Heisenberg antiferromagnet on the triangular lattice by means of density matrix renormalization group (DMRG) simulations. By applying an external Aharonov-Bohm flux insertion in an infinitely long cylinder, we find unambiguous evidence for gapless U (1) Dirac spin liquid behavior. The flux insertion overcomes the finite size restriction for energy gaps and clearly shows gapless behavior at the expected wave-vectors. Using the DMRG transfer matrix, the low-lying excitation spectrum can be extracted, which shows characteristic Dirac cone structures of both spinon-bilinear and monopole excitations. Finally, we confirm that the entanglement entropy follows the predicted universal response under the flux insertion.

Research paper thumbnail of Multistep Approach to Microscopic Models for Frustrated Quantum Magnets: The Case of the Natural Mineral Azurite

Physical Review Letters, 2011

The natural mineral azurite Cu3(CO3)2(OH)2 is a frustrated magnet displaying unusual and controve... more The natural mineral azurite Cu3(CO3)2(OH)2 is a frustrated magnet displaying unusual and controversially discussed magnetic behavior. Motivated by the lack of a unified description for this system, we perform a theoretical study based on density functional theory as well as state-of-the-art numerical many-body calculations. We propose an effective generalized spin-1/2 diamond chain model which provides a consistent description of experiments: low-temperature magnetization, inelastic neutron scattering, nuclear magnetic resonance measurements, magnetic susceptibility as well as new specific heat measurements. With this study we demonstrate that the balanced combination of first principles with powerful many-body methods successfully describes the behavior of this frustrated material.

Research paper thumbnail of Ferromagnetism in a two-component Bose-Hubbard model with synthetic spin-orbit coupling

Physical Review A, 2014

We study the effect of the synthetic spin-orbit coupling in a two-component Bose-Hubbard model in... more We study the effect of the synthetic spin-orbit coupling in a two-component Bose-Hubbard model in one dimension by employing the density-matrix renormalization group method. A ferromagnetic long-range order emerges in both Mott insulator and superfluid phases resulting from the spontaneous breaking of the Z2 symmetry, when the spin-orbit coupling term becomes comparable to the hopping kinetic energy and the intercomponent interaction is smaller than the intracomponent as well. This effect is expected to be detectable with the present realization of the synthetic spin-orbit coupling in experiments.

Research paper thumbnail of Quantized squeezing and even-odd asymmetry of trapped bosons

Physical Review A, 2009

We investigate the exact nature of the superfluid-to-Mott-insulator crossover for interacting bos... more We investigate the exact nature of the superfluid-to-Mott-insulator crossover for interacting bosons on an optical lattice in a one-dimensional, harmonic trap by high-precision density-matrix renormalization-group calculations. The results reveal an intermediate regime characterized by a cascade of microscopic steps. These arise as a consequence of individual boson "squeezing" events and display an even-odd alternation dependent on the trap symmetry. We discuss the experimental observation of this behavior, which is generic in an external trapping potential.

Research paper thumbnail of Exact Results for Intrinsic Electronic Transport in Graphene

Chinese Physics Letters, 2012

We present exact results for the electronic transport properties of graphene sheets connected to ... more We present exact results for the electronic transport properties of graphene sheets connected to two metallic electrodes. Our results, obtained by transfer-matrix methods, are valid for all sheet widths and lengths. In the limit of large width-to-length ratio relevant to recent experiments, we find a Dirac-point conductivity of 2e 2 / √ 3h and a sub-Poissonian Fano factor of 2 -3 √ 3/π ≃ 0.346 for armchair graphene; for the zigzag geometry these are respectively 0 and 1. Our results reflect essential effects from both the topology of graphene and the electronic structure of the leads, giving a complete microscopic understanding of the unique intrinsic transport in graphene.

Research paper thumbnail of Accurate determination of the Gaussian transition in spin-1 chains with single-ion anisotropy

Physical Review B, 2011

The Gaussian transition in the spin-one Heisenberg chain with single-ion anisotropy is extremely ... more The Gaussian transition in the spin-one Heisenberg chain with single-ion anisotropy is extremely difficult to treat, both analytically and numerically. We introduce an improved DMRG procedure with strict error control, which we use to access very large systems. By considering the bulk entropy, we determine the Gaussian transition point to 4-digit accuracy, Dc/J = 0.96845(8), resolving a long-standing debate in quantum magnetism. With this value, we obtain high-precision data for the critical behavior of quantities including the ground-state energy, gap, and transverse string-order parameter, and for the critical exponent, ν = 1.472(2). Applying our improved technique at Jz = 0.5 highlights essential differences in critical behavior along the Gaussian transition line.

Research paper thumbnail of Unusual excitations and double-peak specific heat in a bond-alternating spin-1 K−Γ chain

Physical Review Research, 2021

Research paper thumbnail of Dirac Spin Liquid on the Spin- 1/2 Triangular Heisenberg Antiferromagnet

Physical Review Letters, 2019

We study the spin liquid candidate of the spin-1/2 J1-J2 Heisenberg antiferromagnet on the triang... more We study the spin liquid candidate of the spin-1/2 J1-J2 Heisenberg antiferromagnet on the triangular lattice by means of density matrix renormalization group (DMRG) simulations. By applying an external Aharonov-Bohm flux insertion in an infinitely long cylinder, we find unambiguous evidence for gapless U (1) Dirac spin liquid behavior. The flux insertion overcomes the finite size restriction for energy gaps and clearly shows gapless behavior at the expected wave-vectors. Using the DMRG transfer matrix, the low-lying excitation spectrum can be extracted, which shows characteristic Dirac cone structures of both spinon-bilinear and monopole excitations. Finally, we confirm that the entanglement entropy follows the predicted universal response under the flux insertion.

Research paper thumbnail of Multistep Approach to Microscopic Models for Frustrated Quantum Magnets: The Case of the Natural Mineral Azurite

Physical Review Letters, 2011

The natural mineral azurite Cu3(CO3)2(OH)2 is a frustrated magnet displaying unusual and controve... more The natural mineral azurite Cu3(CO3)2(OH)2 is a frustrated magnet displaying unusual and controversially discussed magnetic behavior. Motivated by the lack of a unified description for this system, we perform a theoretical study based on density functional theory as well as state-of-the-art numerical many-body calculations. We propose an effective generalized spin-1/2 diamond chain model which provides a consistent description of experiments: low-temperature magnetization, inelastic neutron scattering, nuclear magnetic resonance measurements, magnetic susceptibility as well as new specific heat measurements. With this study we demonstrate that the balanced combination of first principles with powerful many-body methods successfully describes the behavior of this frustrated material.

Research paper thumbnail of Ferromagnetism in a two-component Bose-Hubbard model with synthetic spin-orbit coupling

Physical Review A, 2014

We study the effect of the synthetic spin-orbit coupling in a two-component Bose-Hubbard model in... more We study the effect of the synthetic spin-orbit coupling in a two-component Bose-Hubbard model in one dimension by employing the density-matrix renormalization group method. A ferromagnetic long-range order emerges in both Mott insulator and superfluid phases resulting from the spontaneous breaking of the Z2 symmetry, when the spin-orbit coupling term becomes comparable to the hopping kinetic energy and the intercomponent interaction is smaller than the intracomponent as well. This effect is expected to be detectable with the present realization of the synthetic spin-orbit coupling in experiments.

Research paper thumbnail of Quantized squeezing and even-odd asymmetry of trapped bosons

Physical Review A, 2009

We investigate the exact nature of the superfluid-to-Mott-insulator crossover for interacting bos... more We investigate the exact nature of the superfluid-to-Mott-insulator crossover for interacting bosons on an optical lattice in a one-dimensional, harmonic trap by high-precision density-matrix renormalization-group calculations. The results reveal an intermediate regime characterized by a cascade of microscopic steps. These arise as a consequence of individual boson "squeezing" events and display an even-odd alternation dependent on the trap symmetry. We discuss the experimental observation of this behavior, which is generic in an external trapping potential.

Research paper thumbnail of Exact Results for Intrinsic Electronic Transport in Graphene

Chinese Physics Letters, 2012

We present exact results for the electronic transport properties of graphene sheets connected to ... more We present exact results for the electronic transport properties of graphene sheets connected to two metallic electrodes. Our results, obtained by transfer-matrix methods, are valid for all sheet widths and lengths. In the limit of large width-to-length ratio relevant to recent experiments, we find a Dirac-point conductivity of 2e 2 / √ 3h and a sub-Poissonian Fano factor of 2 -3 √ 3/π ≃ 0.346 for armchair graphene; for the zigzag geometry these are respectively 0 and 1. Our results reflect essential effects from both the topology of graphene and the electronic structure of the leads, giving a complete microscopic understanding of the unique intrinsic transport in graphene.

Research paper thumbnail of Accurate determination of the Gaussian transition in spin-1 chains with single-ion anisotropy

Physical Review B, 2011

The Gaussian transition in the spin-one Heisenberg chain with single-ion anisotropy is extremely ... more The Gaussian transition in the spin-one Heisenberg chain with single-ion anisotropy is extremely difficult to treat, both analytically and numerically. We introduce an improved DMRG procedure with strict error control, which we use to access very large systems. By considering the bulk entropy, we determine the Gaussian transition point to 4-digit accuracy, Dc/J = 0.96845(8), resolving a long-standing debate in quantum magnetism. With this value, we obtain high-precision data for the critical behavior of quantities including the ground-state energy, gap, and transverse string-order parameter, and for the critical exponent, ν = 1.472(2). Applying our improved technique at Jz = 0.5 highlights essential differences in critical behavior along the Gaussian transition line.