Bunching Transitions on Vicinal Surfaces and Quantum N-mers

TL;DR

This paper investigates the phase behavior of vicinal crystal surfaces with competing interactions, revealing step bunching phenomena and their quantum analogs, which vary with temperature and interaction ratios.

Contribution

It introduces a model combining short-range attraction and long-range repulsion, predicting step bunching phases and their quantum counterparts, supported by experimental observations.

Findings

Identification of step bunching phases with varying n

Correlation of bunching behavior with temperature and interaction ratios

Observation of quantum n-mers in a bosonic lattice model

Abstract

We study vicinal crystal surfaces with the terrace-step-kink model on a discrete lattice. Including both a short-ranged attractive interaction and a long-ranged repulsive interaction arising from elastic forces, we discover a series of phases in which steps coalesce into bunches of n steps each. The value of n varies with temperature and the ratio of short to long range interaction strengths. We propose that the bunch phases have been observed in very recent experiments on Si surfaces. Within the context of a mapping of the model to a system of bosons on a 1D lattice, the bunch phases appear as quantum n-mers.