Strongly anisotropic roughness in surfaces driven by an oblique particle flux

TL;DR

This paper investigates the anisotropic surface roughness in a growth process driven by an oblique particle flux using field theoretic renormalization, revealing complex phase transitions and directional roughness exponents.

Contribution

It introduces a detailed analysis of anisotropic surface roughness and phase transitions in an oblique flux driven growth process, with new computed roughness exponents and a challenge to prior studies.

Findings

Identification of second order and first order transition lines with a multicritical point.

Calculation of four distinct roughness exponents for different directions.

Results challenge previous understanding of the multicritical behavior.

Abstract

Using field theoretic renormalization, an MBE-type growth process with an obliquely incident influx of atoms is examined. The projection of the beam on the substrate plane selects a "parallel" direction, with rotational invariance restricted to the transverse directions. Depending on the behavior of an effective anisotropic surface tension, a line of second order transitions is identified, as well as a line of potentially first order transitions, joined by a multicritical point. Near the second order transitions and the multicritical point, the surface roughness is strongly anisotropic. Four different roughness exponents are introduced and computed, describing the surface in different directions, in real or momentum space. The results presented challenge an earlier study of the multicritical point.