N-leg spin-S Heisenberg ladders: A density-matrix renormalization group study

作者：Ramos F B^*; Xavier J C

来源：Physical Review B, 2014, 89(9): 094424.

DOI：10.1103/PhysRevB.89.094424

We investigate the N-leg spin-S Heisenberg ladders by using the density matrix renormalization group method. We present estimates of the spin gap Delta(s) and of the ground-state energy per site e(infinity)(N) in the thermodynamic limit for ladders with widths up to six legs and spin S <= 5/2. We also estimate the ground-state energy per site e(infinity)(2D) for the infinite two-dimensional spin-S Heisenberg model. Our results support that for ladders with semi-integer spins the spin excitation is gapless for N odd and gapped for N even, whereas for integer spin ladders the spin gap is nonzero, independent of the number of legs. Those results agree with the well-known conjectures of Haldane and Senechal-Sierra for chains and ladders, respectively. We also observe edge states for ladders with N odd, similar to what happens in spin chains.

• 出版日期2014-3-27