Fig. 2.

The $r$-index as calculated for the Hamiltonian in Eq. 5 with $J_0=J_z=1$ for different system sizes, $L=\mathrm{12,14,16,18}$. In A the $r$-index is plotted as a function of $W$ for zero linear field. In B the $r$-index is plotted as a function of $F$ for a fixed disorder strength $W=0.5$. (Inset) The data plotted as a function of $L\left(F-F_c\right)$ with $F_c=2.2$.