Quantum Antiferromagnets On The Triangular Lattice

this paper, we study the triangular HAF using the exact diagonalization approach. Since first-order SWT supports N'eel type ordering, we also study the second-order SWT to see if the same conclusion holds, and to compare with our numerical results. As mentioned above, due to the frustration, it is extremely difficult to use numerical methods like quantum Monte Carlo to study the triangular HAF, whereas the exact diagonalization approach gives numerically exact results for small finite clusters. Since the results inevitably suffer from finite-size effects, we have to study as large a system as we can and use finite size extrapolation to infer the results in the thermodynamic limit. The largest system size we can diagonalize consists of N = 36 sites. Since it has been suggested [12] that the triangular HAF may be in some sense critical [21], we study a more general anisotropic Hamiltonian, H