arXiv:0707.1195 · Physical Review B
Spontaneous trimerization in a bilinear-biquadratic S=1 zig-zag chain
Philippe Corboz, Andreas Martin Läuchli, Keisuke Totsuka, Hirokazu Tsunetsugu
Abstract
Recent theoretical studies raised the possibility of a realization of spin nematic states in the $S=1$ triangular lattice compound ${\mathrm{NiGa}}_{2}{\mathrm{S}}_{4}$. We study the bilinear-biquadratic spin 1 chain in a zig-zag geometry by means of the density matrix renormalization group method and exact diagonalization. We present the phase diagram focusing on antiferromagnetic interactions. Adjacent to the known Haldane--double Haldane and the extended critical phase with dominant spin nematic correlations we find a trimerized phase with a nonvanishing energy gap. We discuss results for different order parameters, energy gaps, correlation functions, and the central charge, and make connection to field theoretical predictions for the phase diagram.