Corrugation in a molecular C60 monolayer as a frustrated magnet

TL;DR

This study reveals that the corrugation pattern of C60 monolayers on copper surfaces exhibits properties akin to a frustrated triangular Ising antiferromagnet, highlighting complex organization in molecular matter.

Contribution

It demonstrates that molecular corrugation patterns in C60 monolayers can be described by frustrated magnetism models, despite the absence of actual magnetic interactions.

Findings

Corrugation patterns match frustrated Ising spin models

C60/Cu system exhibits characteristics of a triangular Ising antiferromagnet

Molecular organization shows features of highly frustrated magnetic systems

Abstract

Under certain experimental conditions, the deposition of C60 molecules onto an atomically flat copper surface gives rise to the formation of corrugated islands. This corrugation, which reflects a molecular displacement perpendicular to the surface plane, presents an astonishing pattern: it is well described by a frustrated Ising spin Hamiltonian whose thermodynamics is compatible with a spin liquid about to transit towards an ordered zigzag state. Here we study the statistical properties of such a molecular corrugation using tools generally employed in frustrated magnetism. More specifically, the real and reciprocal space analysis of pairwise molecule correlations allows us to demonstrate that the C60/Cu system, in which magnetism is totally absent, has all the characteristics of a triangular Ising antiferromagnet. Our results indicate that the organization of two-dimensional matter, at the molecular length scale, sometimes turns out to be particularly close to that encountered in highly frustrated magnets.