Quantum Chaos in the Heisenberg Spin Chain: the Effect of   Dzyaloshinskii-Moriya Interaction
  Using one-dimensional spin-1/2 systems as prototypes of quantum many-body systems, we study the emergence of quantum chaos. The main purpose of this work is to answer the following question: how does the spin-orbit interaction, as a pure quantum interaction, may lead to the onset of quantum chaos? We consider three integrable spin-1/2 systems: the Ising, the XX, and the XXZ limits, and analyze whether quantum chaos develops or not after the addition of the Dzyaloshinskii-Moriya interaction. We find that, depending on the strength of the anisotropy parameter, the answer is positive for the XXZ and Ising models, while no such evidence is observed for the XX model. We also discuss the relationship between quantum chaos and thermalization. 
J. Vahedi, A. Ashouri and S. Mahdavifar
cond-mat.stat-mech