No abstract

We study the emergence of edge-magnetism in zigzag nanoribbons from electron-electron interactions in a minimal 3-band tight-binding descrip¬tion of transition-metal dichalcogenide monolayers with an intra-orbital Hub¬bard term. We explain the influence of each orbital in the magnetic ordering, comparing the results of Mean Field Theory and determinant Quantum Monte Carlo. We focus on a gapped edge-antiferromagnetic phase appearing at three-quarter edge-filling for realistic values of the interaction.

The proliferation of quantum fluctuations and long-range entanglement presents an outstanding challenge for the numerical simulation of interacting spin systems with exotic ground states. Here, we present a Chebyshev iterative method that gives access to the thermodynamic properties and critical behavior of frustrated quantum spin models with good accuracy. The computational complexity scales linearly with the Hilbert space dimension and the number of Chebyshev iterations used to approximate the eigenstates. Using this approach, we calculate the spin correlations of the Kitaev-Heisenberg model, a paradigmatic model of honeycomb iridates that exhibits a rich phase diagram including a quantum spin liquid phase. Our results are benchmarked against exact diagonalization and a popular iterative method based on thermal pure quantum (TPQ) states. All methods accurately predict a transition to a stripy (spin-liquid) phase for the critical value of the Kitaev coupling J K ≈ −1.3J H (J K ≈ −8.0J H ) for honeycomb layers with ferromagnetic Heisenberg interactions (J H > 0). Our findings suggest that a hybrid Chebyshev-TPQ approach could open the door to previously unattainable studies of quantum spin models in two dimensions.