Fabricating Multiscale Quasiperiodic Architectures: Artificial Spin-Ice and Molecular Thin Films

Chandler, Liam (2025) Fabricating Multiscale Quasiperiodic Architectures: Artificial Spin-Ice and Molecular Thin Films PhD thesis, University of Liverpool.

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Abstract

This thesis addresses the challenge of studying quasicrystal surfaces for potential applications by fabricating atomic- and nanoscale quasiperiodic (QP) architectures. Measuring the surfaces of natural quasicrystals presents significant experimental barriers, including scarcity, ultra-high vacuum requirements, and extensive surface preparation. There is therefore a need to fabricate quasiperiodic architectures that physically model quasicrystal surfaces, enabling access to fundamental properties and the exploration of potential applications. Fabrication of multiscale QP architectures is achieved with nanolithography of nanomagnetic arrays and molecular deposition on real quasicrystal surfaces. These investigations reveal interesting properties such as forced excitation and anisotropic adsorption. An important advance is the establishment of a protocol for fabricating nano-scale QP tilings with thermal-scanning probe lithography (t-SPL), a nanolithography technique, for new researchers to the field. By optimising the design, chemical, and physical challenges, reproducibly high quality and complex QP tilings are fabricated. Next, the nanomagnetic properties of nano-lithograped 8-fold Ammann-Beenker (ABT) and 4-fold Square Fibonacci (SFT) artificial spin-ice tilings are investigated with micromagnetic modelling, magnetic force microscopy (MFM), and X-ray magnetic circular dichroism-photoemission electron microscopy (XMCD-PEEM). Investigations reveal forced excitations within ground state domains of the ABT, and pinned high-energy states stabilised by quasiperiodic structure within the SFT. These phenomena have the potential to be applied to neuromorphic computing architectures. Finally, by depositing molecular C60 on the surface of the annealed 2-fold Al-Ni-Co quasicrystal surface, the first demonstration of anisotropic chains of C60 with quasiperiodic separations are formed, as measured with scanning tunneling microscopy. This result advances the potential for molecular electronics of functional endofullerines on quasicrystal surfaces. This work demonstrates how fabricating multiscale quasiperiodic architectures enables the crucial investigation of fundamental physics and advances potential applications.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	ammann-beenker tiling, artificial spin-ice, decagonal, mfm, nanolithography, nanomagnetism, quasicrystal, sem, square fibonacci tiling, thermal scanning probe lithography, thin film growth, xmcd-peem
Divisions:	Faculty of Science & Engineering Faculty of Science & Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	01 Dec 2025 15:28
Last Modified:	01 Dec 2025 15:56
DOI:	10.17638/03194679
Supervisors:	Sharma, Hem McGrath, Ronan O'Brien, Liam
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3194679
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