Fig. 2: Quasiperiodic Potts (q = 3) and Ising (q = 2) chains.
From: Universality and quantum criticality in quasiperiodic spin chains

For the Ising chain we choose a potential with both positive and negative couplings, whereas for the Potts chain all couplings are taken to be antiferromagnetic. a Scaling collapse of the probability of the RG to end in a paramagnetic phase for the Potts model, with ν = 1. Here, g = Wh/WJ is an asymmetry parameter between hi and Ji with WJ,h the amplitude of the quasiperiodic potentials and gc = 1. Inset: Raw, uncollapsed data. b Spin–spin correlation function \(\left\langle {\sigma \left( L \right)\sigma \left( 0 \right)} \right\rangle\) averaged over the uncorrelated phases θJ, θh, scaling as L−0.47 for Potts (in good agreement with (6) derived for discrete Fibonacci sequences) and L−0.9 for Ising. Error bars represent SE. c Energy-length scaling: ΔE ~ L−0.22 ln L for Potts, whereas the Ising transition has a finite dynamical exponent z ≈ 1.6.