Disorder driven phase transitions of the large q-state Potts model in 3d

TL;DR

This paper investigates how disorder influences phase transitions in the large-q Potts model in 3D, revealing a transition from first-order to second-order with universal critical exponents under strong disorder.

Contribution

It provides analytical and numerical evidence for disorder-induced softening of phase transitions and identifies universal critical exponents in the critical regime.

Findings

Transition remains first order with disorder but shows essential singularities.

Strong disorder softens the transition into second order with non-homogeneous phases.

Universal critical exponents are b2/ =0.60(2) and =0.73(1).

Abstract

Phase transitions induced by varying the strength of disorder in the large-q state Potts model in 3d are studied by analytical and numerical methods. By switching on the disorder the transition stays of first order, but different thermodynamical quantities display essential singularities. Only for strong enough disorder the transition will be soften into a second-order one, in which case the ordered phase becomes non-homogeneous at large scales, while the non-correlated sites percolate the sample. In the critical regime the critical exponents are found universal: \beta/\nu=0.60(2) and \nu=0.73(1).