Facet ridge end points in crystal shapes

TL;DR

This paper investigates the complex equilibrium crystal shapes near facet ridge end points using a modified solid-on-solid model, revealing the instability of simplified models and the intricate nature of the actual ECS.

Contribution

It introduces a uniaxial interaction extension to the BCSOS model and analyzes the stability of the stochastic FRE point, showing the generic ECS's complex features.

Findings

The stochastic FRE point is unstable.

Generic ECS contains first-order ridges and coexistence of rough orientations.

Boundaries terminate in Pokrovsky-Talapov type end points.

Abstract

Equilibrium crystal shapes (ECS) near facet ridge end points (FRE) are generically complex. We study the body-centered solid-on-solid model on a square lattice with an enhanced uniaxial interaction range to test the stability of the so-called stochastic FRE point where the model maps exactly onto one dimensional Kardar-Parisi-Zhang type growth and the local ECS is simple. The latter is unstable. The generic ECS contains first-order ridges extending into the rounded part of the ECS, where two rough orientations coexist and first-order faceted to rough boundaries terminating in Pokrovsky-Talapov type end points.