Coupling-dependent antiferromagnetic-ferromagnetic ordering in a pinwheel artificial spin ice

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Hauptverfasser: Strømberg, Anders, Digernes, Einar, Chopdekar, Rajesh Vilas, Grepstad, Jostein, Folven, Erik
Format: Preprint
Veröffentlicht: 2024
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author Strømberg, Anders
Digernes, Einar
Chopdekar, Rajesh Vilas
Grepstad, Jostein
Folven, Erik
author_facet Strømberg, Anders
Digernes, Einar
Chopdekar, Rajesh Vilas
Grepstad, Jostein
Folven, Erik
contents Nanopatterned magnetic thin films offer a platform for exploration of tailored magnetic properties such as emergent long-range order. A prominent example is artificial spin ice (ASI), where an arrangement of nanoscale magnetic elements, acting as macrospins, interact via their dipolar fields. In this study, we discuss the transition from antiferromagnetic (AFM) to ferromagnetic (FM) long-range order in a square lattice ASI, as the magnetic elements are gradually rotated through 45° to a "pinwheel" configuration. The AFM$\unicode{x2013}$FM transition is observed experimentally using synchrotron radiation x-ray spectromicroscopy and occurs for a certain rotation angle of the nanomagnets, dependent on the dipolar coupling strength determined by the separation of the magnets in the lattice. Large-scale magnetic dipole simulations show that the point-dipole approximation fails to capture the correct AFM$\unicode{x2013}$FM transition angle. However, excellent agreement with experimental data is obtained using a dumbbell-dipole model which better reflects the actual dipolar fields of the magnets. This model also explains the coupling dependence of the transition angle, another feature not captured by the point-dipole model. Our findings resolve a discrepancy between measurement and theory in previous work on "pinwheel" ASIs and establish the coupling dependence of the AFM-FM transition. The revised dipole model, with a more accurate representation of the stray field, offers more precise control of magnetic order in artificial spin systems.
format Preprint
id arxiv_https___arxiv_org_abs_2404_03973
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Coupling-dependent antiferromagnetic-ferromagnetic ordering in a pinwheel artificial spin ice
Strømberg, Anders
Digernes, Einar
Chopdekar, Rajesh Vilas
Grepstad, Jostein
Folven, Erik
Mesoscale and Nanoscale Physics
Nanopatterned magnetic thin films offer a platform for exploration of tailored magnetic properties such as emergent long-range order. A prominent example is artificial spin ice (ASI), where an arrangement of nanoscale magnetic elements, acting as macrospins, interact via their dipolar fields. In this study, we discuss the transition from antiferromagnetic (AFM) to ferromagnetic (FM) long-range order in a square lattice ASI, as the magnetic elements are gradually rotated through 45° to a "pinwheel" configuration. The AFM$\unicode{x2013}$FM transition is observed experimentally using synchrotron radiation x-ray spectromicroscopy and occurs for a certain rotation angle of the nanomagnets, dependent on the dipolar coupling strength determined by the separation of the magnets in the lattice. Large-scale magnetic dipole simulations show that the point-dipole approximation fails to capture the correct AFM$\unicode{x2013}$FM transition angle. However, excellent agreement with experimental data is obtained using a dumbbell-dipole model which better reflects the actual dipolar fields of the magnets. This model also explains the coupling dependence of the transition angle, another feature not captured by the point-dipole model. Our findings resolve a discrepancy between measurement and theory in previous work on "pinwheel" ASIs and establish the coupling dependence of the AFM-FM transition. The revised dipole model, with a more accurate representation of the stray field, offers more precise control of magnetic order in artificial spin systems.
title Coupling-dependent antiferromagnetic-ferromagnetic ordering in a pinwheel artificial spin ice
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2404.03973