Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physica A Statistical Mechanics and its Applications

Magnetic properties of an Ising ladder-like graphene nanoribbon by using Monte Carlo method

Min Young Yang, Wei Wang, Bo-chen Li, Hao-Jia Wu, Shao-qing Yang, Jun Jie Yang

Published Sep 26, 2019• 72 citations
Publisher
DOI
10.1016/j.physa.2019.122932

Related papers

The exact solution of the edge-modified graphene nanoribbon-like structure Ising-Heisenberg spin (1,1/2) system

Da-cheng Ma, An Du

Physica E Low-dimensional Systems and Nanostructures•Nov 10, 2022•7 citations

Unique magnetism in a graphene ladder-type Ising system under an applied transverse field

T. Kaneyoshi

Journal of Magnetism and Magnetic Materials•Apr 27, 2019•19 citations

Quantum phase transitions in effective spin-ladder models for graphene zigzag nanoribbons

Cornelie Koop, Stefan Weßel

We examine the magnetic correlations in quantum spin models that were derived recently as effective low-energy theories for electronic correlation effects on the edge states of graphene nanoribbons. For this purpose, we employ quantum Monte Carlo simulations to access the large-distance properties, accounting for quantum fluctuations beyond mean-field-theory approaches to edge magnetism. For certain chiral nanoribbons, antiferromagnetic interedge couplings were previously found to induce a gapped quantum disordered ground state of the effective spin model. We find that the extended nature of the intraedge couplings in the effective spin model for zigzag nanoribbons leads to a quantum phase transition at a large, finite value of the interedge coupling. This quantum critical point separates the quantum disordered region from a gapless phase of stable edge magnetism at weak intraedge coupling, which includes the ground states of spin-ladder models for wide zigzag nanoribbons. To study the quantum critical behavior, the effective spin model can be related to a model of two antiferromagnetically coupled Haldane-Shastry spin-half chains with long-ranged ferromagnetic intrachain couplings. The results for the critical exponents are compared also to several recent renormalization-group calculations for related long-ranged interacting quantum systems.

arXiv:1707.05522•Physical review. B./Physical review. B•Oct 9, 2017•16 citations

Magnetic Properties of Quasi-One-Dimensional Crystals Formed by Graphene Nanoclusters and Embedded Atoms of the Transition Metals

Vladyslav O. Cheranovskii, Victor V. Slavin, E. V. Ezerskaya +2 more

Using the density-matrix renormalization group method and quantum Monte Carlo simulation, we studied numerically the energy spectrum and thermodynamics of the quantum Heisenberg spin model for narrow graphene nanoribbons and their derivatives with periodically embedded heteroatoms. For several nanoribbon structures we found macroscopic ground state spin, gapless lowest excitation spectra and intermediate magnetization plateaus at low temperatures. We also studied the lowest energy states of frustrated systems formed by triangular graphitic clusters connected by bridged ions of transition metals. On the base of many-body perturbation theory and the exact diagonalization method, we showed the possibility of spin switching for this model due to the change the corresponding coupling parameters.

Crystals•May 15, 2019•11 citations

Magnetization distribution in a spin ladder-shaped quantum nanomagnet

Karol Szałowski, P. Kowalewska

arXiv:1803.08835•Journal of Magnetism and Magnetic Materials•Sep 5, 2018•4 citations

Quantum Monte Carlo studies of novel phases in strongly correlated systems

Zi Yang Meng

Three models of strongly correlated electron systems have been studied in this thesis: the Shastry-Sutherland quantum antiferromagnet, the quantum spin liquid emerging out of correlated Dirac fermions on the honeycomb lattice, and the edge-state magnetism in the graphene nanoribbons. The methods applied are quantum Monte Carlo simulations, namely, stochastic series expansion quantum Monte Carlo for bosonic (spin) systems and projector auxiliary field quantum Monte Carlo for fermionic systems. The stochastic series expansion quantum Monte Carlo method is applied to study the ground state properties as well as the magnetization process of the spin-1/2 easy-axis Heisenberg model on the Shastry-Sutherland lattice. The quantum phase transitions between a N\'eel state, a dimer triplet state and a ferromagnetic XY phase have been characterized by finite size scaling analysis. The crystalline structures of the triplon magnetic excitations in the magnetic plateaus have been identified. The projector auxiliary field quantum Monte Carlo is applied to explore the ground state phase diagram of the SU(2) Hubbard model on the honeycomb lattice. The interplay between the relativistic Dirac dispersion, the vanishing density of states at half-filling and the strong quantum fluctuations, drives the system from a semimetal at weak coupling to an antiferromagnetic Mott insulator in the strong coupling regime. In between these phases there emerges an unexpected quantum spin liquid with no symmetry breaking in any channel. After careful finite size scaling analysis of various correlation functions, the quantum spin liquid phase is characterized as a short-range resonating valence bond state with a finite spin gap to all magnetic excitations. The study of edge-state magnetism in graphene nanoribbons is more experimentally motivated. The projector auxiliary field quantum Monte Carlo method is used to measure the static spin-spin correlation function, the single-particle spectral function, as well as the dynamic spin structure factor along the zigzag edge of graphene nanoribbons. A dominant low energy peak generated by the Coulomb interaction in the single-particle spectral function is identified as the dynamical signature of edge-state magnetism. The magnetic excitations along the zigzag edge show a linear dispersion at low energies due to the effective antiferromagnetic coupling of the edges across the ribbon. The magnetic excitations are damped by scattering processes into the particle-hole continuum at high energies.

•Jan 1, 2011•0 citations
We examine the magnetic correlations in quantum spin models that were derived recently as effective low-energy theories for electronic correlation effects on the edge states of graphene nanoribbons. For this purpose, we employ quantum Monte Carlo simulations to access the large-distance properties, accounting for quantum fluctuations beyond mean-field-theory approaches to edge magnetism. For certain chiral nanoribbons, antiferromagnetic interedge couplings were previously found to induce a gapped quantum disordered ground state of the effective spin model. We find that the extended nature of the intraedge couplings in the effective spin model for zigzag nanoribbons leads to a quantum phase transition at a large, finite value of the interedge coupling. This quantum critical point separates the quantum disordered region from a gapless phase of stable edge magnetism at weak intraedge coupling, which includes the ground states of spin-ladder models for wide zigzag nanoribbons. To study the quantum critical behavior, the effective spin model can be related to a model of two antiferromagnetically coupled Haldane-Shastry spin-half chains with long-ranged ferromagnetic intrachain couplings. The results for the critical exponents are compared also to several recent renormalization-group calculations for related long-ranged interacting quantum systems.
Using the density-matrix renormalization group method and quantum Monte Carlo simulation, we studied numerically the energy spectrum and thermodynamics of the quantum Heisenberg spin model for narrow graphene nanoribbons and their derivatives with periodically embedded heteroatoms. For several nanoribbon structures we found macroscopic ground state spin, gapless lowest excitation spectra and intermediate magnetization plateaus at low temperatures. We also studied the lowest energy states of frustrated systems formed by triangular graphitic clusters connected by bridged ions of transition metals. On the base of many-body perturbation theory and the exact diagonalization method, we showed the possibility of spin switching for this model due to the change the corresponding coupling parameters.
Three models of strongly correlated electron systems have been studied in this thesis: the Shastry-Sutherland quantum antiferromagnet, the quantum spin liquid emerging out of correlated Dirac fermions on the honeycomb lattice, and the edge-state magnetism in the graphene nanoribbons. The methods applied are quantum Monte Carlo simulations, namely, stochastic series expansion quantum Monte Carlo for bosonic (spin) systems and projector auxiliary field quantum Monte Carlo for fermionic systems. The stochastic series expansion quantum Monte Carlo method is applied to study the ground state properties as well as the magnetization process of the spin-1/2 easy-axis Heisenberg model on the Shastry-Sutherland lattice. The quantum phase transitions between a N\'eel state, a dimer triplet state and a ferromagnetic XY phase have been characterized by finite size scaling analysis. The crystalline structures of the triplon magnetic excitations in the magnetic plateaus have been identified. The projector auxiliary field quantum Monte Carlo is applied to explore the ground state phase diagram of the SU(2) Hubbard model on the honeycomb lattice. The interplay between the relativistic Dirac dispersion, the vanishing density of states at half-filling and the strong quantum fluctuations, drives the system from a semimetal at weak coupling to an antiferromagnetic Mott insulator in the strong coupling regime. In between these phases there emerges an unexpected quantum spin liquid with no symmetry breaking in any channel. After careful finite size scaling analysis of various correlation functions, the quantum spin liquid phase is characterized as a short-range resonating valence bond state with a finite spin gap to all magnetic excitations. The study of edge-state magnetism in graphene nanoribbons is more experimentally motivated. The projector auxiliary field quantum Monte Carlo method is used to measure the static spin-spin correlation function, the single-particle spectral function, as well as the dynamic spin structure factor along the zigzag edge of graphene nanoribbons. A dominant low energy peak generated by the Coulomb interaction in the single-particle spectral function is identified as the dynamical signature of edge-state magnetism. The magnetic excitations along the zigzag edge show a linear dispersion at low energies due to the effective antiferromagnetic coupling of the edges across the ribbon. The magnetic excitations are damped by scattering processes into the particle-hole continuum at high energies.