1206.2044 (D. Galanakis et al.)

Order and supersymmetry at high filling zero energy states on the
triangular lattice    [PDF]

D. Galanakis, C. L. Henley, S. Papanikolaou

We perform exact diagonalization studies for a system of hard-core and nearest-neighbor excluding fermions at a fine-tuned regime where an exact non-relativistic supersymmetry is displayed. We study the behavior of the ground-state subspace, as the filling is altered. We confirm previous results that at a density interval in intermediate fillings, the system displays a large, exponentially increasing with the system size, degeneracy of zero energy ground-states, which maximizes at ~0.175. We confirm that the lower limit of that interval is 1/7 consistently with previous suggestions, but the upper limit slightly violates a recent conjecture that it is 1/5. We focus on the behavior of these high density ground states (> 1/5) and we find evidence that non-trivial spatial order typically develops, seemingly robust as the system size increases.

View original: http://arxiv.org/abs/1206.2044