Phase transition in Heisenberg stacked triangular antiferromagnets: End of a controversy

By using the Wang-Landau flat-histogram Monte Carlo (MC) method for very large lattice sizes never simulated before, we show that the phase transition in the frustrated Heisenberg stacked triangular antiferromagnet is of first order, contrary to results of earlier MC simulations using old-fashioned methods. Our result lends support to the conclusion of a nonperturbative renormalization group performed on an effective Hamiltonian. It puts an end to a $20\text{−}\text{year}$-long controversial issue.

Figure 1

Energy histogram for $N=96$ at $T_c$ indicated in the figure.

Figure 2

Energy histogram for $N=120$ at $T_c$ indicated in the figure.

Figure 3

Energy histogram for $N=150$ at $T_c$ indicated in the figure.

Figure 4

Energy versus $T$ for $N=96,120,150$.

Figure 5

Magnetization versus $T$ for $N=96,120,150$.

Figure 6

Susceptibility versus $T$ for $N=96,120,150$.

Figure 7

Maximum of susceptibility versus $N=96$, 108, 120, and 150 on a ln-ln scale. The slope is 3.1. See text for comments.