Rough or crumpled: Strong coupling phases of a generalized Kardar-Parisi-Zhang surface

TL;DR

This paper investigates a generalized KPZ equation in two dimensions, revealing two strong coupling phases—rough and crumpled—with distinct structural properties and nonuniversal scaling behaviors.

Contribution

It introduces a new generalized KPZ model exhibiting multiple strong coupling phases and characterizes their structural and scaling properties.

Findings

Identifies rough and crumpled phases with distinct order properties

Shows nonuniversal scaling exponents in the rough phase

Demonstrates the existence of a weak coupling phase

Abstract

We study a generalized Kardar-Parisi-Zhang (KPZ) equation [Jana et al., Phys. Rev. E 109, L032104 (2024)] that sets the paradigm for universality in roughening of growing nonequilibrium surfaces without any conservation laws but with competing local and nonlocal nonlinear effects. This equation in two dimensions exhibits two distinct strong coupling regimes: a rough phase and a crumpled phase, in addition to a weak coupling phase. The conformation fluctuations of such a rough surface are given by nonuniversal scaling exponents, with orientational long-range order and positional short-range order, whereas the crumpled phase has positional and orientational short-range order.