In search of multipolar order on the Penrose tiling

TL;DR

This study uses Monte Carlo simulations to investigate multipolar order on the Penrose tiling, finding only short-range order despite initial indications of long-range correlations, which challenges previous assumptions.

Contribution

It provides the first detailed analysis of multipolar ordering on the Penrose tiling, revealing the absence of long-range order in these systems.

Findings

Long-range multipolar order is absent in the studied systems.

Initial indications of order are due to superstructures, not true long-range order.

Results serve as a caution for future studies of multipoles on quasiperiodic templates.

Abstract

Based on Monte Carlo calculations, multipolar ordering on the Penrose tiling, relevant for two-dimensional molecular adsorbates on quasicrystalline surfaces and for nanomagnetic arrays, has been analyzed. These initial investigations are restricted to multipolar rotors of rank one through four - described by spherical harmonics Ylm with l=1...4 and restricted to m=0 - positioned on the vertices of the rhombic Penrose tiling. At first sight, the ground states of odd-parity multipoles seem to exhibit long-range multipolar order, indicated by the appearance of a superstructure in the form of the decagonal Hexagon-Boat-Star tiling, in agreement with previous investigations of dipolar systems. Yet careful analysis establishes that long-range multipolar order is absent in all cases investigated here, and only short-range order exists. This result should be taken as a warning for any future analysis of order in either real or simulated arrangements of multipoles on quasiperiodic templates.