Incommensurate correlations in the anisotropic triangular Heisenberg lattice

We study the anisotropic spin-1/2 antiferromagnetic triangular Heisenberg lattice in two dimensions, seen as a set of chains with couplings J (J^') along (in-between) chains, respectively. Our focus is on the incommensurate correlation that emerges in this system in a wide parameter range due to the intrinsic frustration of the spins. We study this system with traditional density matrix renormalization group using cylindrical boundary conditions to least constrain possible incommensurate order. Despite that the limit of essentially decoupled chains J^'/J0.5 is not very accessible numerically, it appears that the spin-spin correlations remain incommensurate for any finite 0<J^'<J_^C^', where J_^C^'/J>1. The incommensurate wave vector qJ, however, approaches the commensurate value corresponding to the antiferromagnetic correlation of a single chain very rapidly with decreasing J^'/J, roughly as qJ~π-c₁(J^'/J)ⁿe^-c₂J/J^'.