2015/03/13 by Wojciech Brzezicki, Brzezicki, Wojciech, Imre Hagymási +5
Physics and Astronomy · #FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.1503.04031
11 pages, 12 figures
arxiv created 2015/03/13 · arxiv updated 2016/08/08
We add a Heisenberg interaction term ∝λ in the one-dimensional SU(2)⊗XY spin-orbital model introduced by B. Kumar. At λ=0 the spin and orbital degrees of freedom can be separated by a unitary transformation leading to an exact solution of the model. We show that a finite λ>0 leads to spontaneous dimerization of the system which in the thermodynamic limit becomes a smooth phase transition at λ→ 0, whereas it remains discontinuous within the first order perturbation approach. We present the behavior of the entanglement entropy, energy gap and dimerization order parameter in the limit of λ→ 0 confirming the critical behavior. Finally, we show the evidence of another phase transition in the Heisenberg limit, λ→∞, and give a qualitative analytical explanation of the observed dimerized states both in the limit of small and large λ.