Quantum wetting transitions in two dimensions: an alternative path to non-universal interfacial singularities

TL;DR

This paper explores quantum wetting transitions in two-dimensional systems, revealing a phase diagram with a quantum critical point and distinct thermal and quantum fluctuation regimes, providing new insights into non-universal interfacial critical behavior.

Contribution

It introduces an effective interfacial model analyzed via functional renormalization-group, uncovering a finite temperature phase diagram with a quantum critical point in 2D wetting transitions.

Findings

Identification of a line of interface unbinding transitions terminating at T=0

Distinct scaling regimes due to quantum and thermal fluctuations

Quantum critical regime shows universal behavior, unlike non-universal classical regimes

Abstract

We consider two-dimensional ($d=2$) systems with short-ranged microscopic interactions, where interface unbinding (wetting) transitions occur in the limit of vanishing temperature $T$. For $T=0$ the transition is characterized by non-universal critical properties analogous to those established for thermal wetting transitions in $d=3$, albeit with a redefined capillary parameter $\tilde{\omega}$. Within a functional renormalization-group treatment of an effective interfacial model, we compute the finite temperature phase diagram, exhibiting a line of interface unbinding transitions, terminating at $T=0$ with an interfacial quantum critical point. At finite $T$ we identify distinct scaling regimes, reflecting the interplay between quantum and thermal interfacial fluctuations. A crossover line marking the onset of the quantum critical regime is described by the $d=3$ interfacial correlation-length exponent $\nu_{||}$. This opens a new way to investigate the non-universal character of $\nu_{||}$ without penetrating the true critical regime. On the other hand, the emergent interfacial quantum critical regime shows no signatures of non-universality.