Far-from-equilibrium growth of thin films in a temperature gradient

TL;DR

This study investigates the irreversible growth of thin films under a temperature gradient, revealing a new universality class of phase transition with unique critical behavior and growth dynamics.

Contribution

It introduces a novel analysis of far-from-equilibrium thin film growth in a temperature gradient, identifying a new universality class and growth mechanisms.

Findings

Discovered a continuous phase transition driven by temperature gradient

Identified critical temperature T_c=0.84(2) with unique critical exponents

Analyzed growth dynamics using a bond model revealing asymmetries and transverse ordering

Abstract

The irreversible growth of thin films under far-from-equilibrium conditions is studied in $(2+1)-$dimensional strip geometries. Across one of the transverse directions, a temperature gradient is applied by thermal baths at fixed temperatures between $T_1$ and $T_2$, where $T_1<T_c^{hom}<T_2$ and $T_c^{hom}=0.69(1)$ is the critical temperature of the system in contact with an homogeneous thermal bath. By using standard finite-size scaling methods, we characterized a continuous order-disorder phase transition driven by the thermal bath gradient with critical temperature $T_c=0.84(2)$ and critical exponents $\nu=1.53(6)$, $\gamma=2.54(11)$, and $\beta=0.26(8)$, which belong to a different universality class from that of films grown in an homogeneous bath. Furthermore, the effects of the temperature gradient are analyzed by means of a bond model that captures the growth dynamics. The interplay of geometry and thermal bath asymmetries leads to growth bond flux asymmetries and the onset of transverse ordering effects that explain qualitatively the shift in the critical temperature.