Kitaev–Ising-J1-J2 Model: A Density Matrix Renormalization Group Study

We numerically study the Kitaev honeycomb model with the additional XX Ising interaction between the nearest and the next nearest neighbors (Kitaev–Ising- $${{J}_{1}}$$ - $${{J}_{2}}$$ model), by using the density matrix renormalization group method. Such additional interaction correspond to the nearest and diagonal interactions on the square lattice. Phase diagram of the bare Kitaev model consist of low entangled commensurate magnetic phases and entangled Kitaev spin liquid. Anisotropic Ising interaction allows the entangled quantum paramagnetic phases in the phase diagram, which in the absence of the magnetic field previously was predicted for more complex type of interaction. We study the scaling law of the entanglement entropy and the bond dimension of the matrix product state with the size of the system. In addition, we propose an optimization algorithm to prevent density matrix renormalization group (DMRG) from getting stuck in the low-entangled phases.