Self-organization of adatom adsorption structure at interaction with tip of dynamic force microscope

TL;DR

This paper models the spontaneous formation of adatom structures in dynamic force microscopy as a first-order phase transition driven by shear strain and temperature, using synergetic equations and viscoelastic theory.

Contribution

It introduces a theoretical framework linking shear strain, temperature, and shear modulus to adatom structure formation via synergetic equations and phase transition analysis.

Findings

Adatom adsorption structure forms as a first-order transition.

Critical temperature depends linearly on shear modulus.

Shear strain acts as the order parameter in the model.

Abstract

The formation of an adatom adsorption structure in dynamic force microscopy experiment is shown as a result of the spontaneous appearance of shear strain caused by external supercritical heating. This transition is described by the Kelvin-Voigt equation for a viscoelastic medium, the relaxation Landau-Khalatnikov equation for shear stress, and the relaxation equation for temperature. It is shown that these equations formally coincide with the synergetic Lorenz system, where the shear strain acts as the order parameter, the conjugate field is reduced to the stress, and the temperature is the control parameter. Within the adiabatic approximation, the steady-state values of these quantities are found. Taking into account the sample shear modulus vs strain dependence, the formation of the adatom adsorption configuration is described as the first-order transition. The critical temperature of the tip linearly increases with the growth of the effective value of the sample shear modulus and decreases with the growth of its typical value.