Phase diagram of step faceting for sticky steps

Noriko Akutsu

doi:10.1063/1.4943400

paper

Phase diagram of step faceting for sticky steps

arXiv:1510.00899 · doi:10.1063/1.4943400

Abstract

A phase diagram for the step faceting phase, the step droplet phase, and the Gruber-Mullins-Pokrovsky-Talapov (GMPT) phase on a crystal surface is obtained by calculating the surface tension with the density matrix renormalization group method. The model based on the calculations is the restricted solid-on-solid (RSOS) model with a point-contact-type step-step attraction (p-RSOS model) on a square lattice. The point-contact-type step-step attraction represents the energy gain obtained by forming a bonding state with orbital overlap at the meeting point of the neighbouring steps. Owing to the sticky character of steps, there are two phase transition temperatures, $T_{f, 1}$ and $T_{f, 2}$ . At temperatures $T < T_{f, 1}$ , the anisotropic surface tension has a disconnected shape around the (111) surface. At $T < T_{f, 2} < T_{f, 1}$ , the surface tension has a disconnected shape around the (001) surface. On the (001) facet edge in the step droplet phase, the shape exponent normal to the mean step running direction $θ_{n} = 2$ at $T$ near $T_{f, 2}$ , which is different from the GMPT universal value $θ_{n} = 3/2$ . On the (111) facet edge, $θ_{n} = 4/3$ only on $T_{f, 1}$ . To understand how the system undergoes phase transition, we focus on the connection between the p-RSOS model and the one-dimensional spinless quasi-impenetrable attractive bosons at absolute zero.

26 pages, 15 figures

Phase diagram of step faceting for sticky steps

Abstract

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