Ice-rule made manifold: phase transitions, topological defects and manifold restoration in two-dimensional artificial spin systems

Abstract

Artificial spin ices are arrays of correlated nano-scale magnetic islands that prove an excellent playground in which to study the role of topology in critical phenomena. Here, we investigate a continuum of spin ice geometries, parameterised by rotation of the islands. In doing so, we morph from the classic square ice to the recently studied pinwheel geometry, with the rotation angle acting as a proxy for controlling inter-island interactions. We experimentally observe a change in ground state magnetic order from antiferromagnetic to ferromagnetic across this class of geometries using Lorentz transmission electron microscopy on thermally annealed cobalt arrays. The change in ordering leads to an apparent change in the nature of the defects supported: from one-dimensional strings in the antiferromagnetic phase to two-dimensional vortex-like structures in the ferromagnetic one, consistent with the scaling predicted by the Kibble-Zurek mechanism. Our results show how magnetic order in artificial spin ices can be tuned by changes in geometry so that a truly frustrated ice-rule phase is possible in two-dimensional systems. Furthermore, we demonstrate this system as a testbed to investigate out-of-equilibrium dynamics across phases.

arXiv comment18 pages, 5 figures

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Cited by in corpus (12)

• Kibble-Zurek Mechanism for Nonequilibrium Phase Transitions in Driven Systems with Quenched Disorder
• Quenched Dynamics of Artificial Spin Ice: Coarsening versus Kibble-Zurek
• Spin-wave dynamics and symmetry breaking in an artificial spin ice
• Topology Restricts Quasidegeneracy in Sheared Square Colloidal Ice
• Artificial Spin Ice: A Tutorial on Design and Control of Geometry, Microstate, Magnon Dynamics & Neuromorphic Computing
• Violation of the fluctuation-dissipation theorem and effective temperatures in spin ice
• Writable spin wave nanochannels in an artificial-spin-ice-mediated ferromagnetic thin film
• Bilayer artificial spin ice: magnetic force switching and basic thermodynamics
• Tailoring magnetization reversal of a single-domain bar nanomagnet via its end geometry
• Magnetic Order and Long-Range Interactions in Mesoscopic Ising Chains
• Field-driven Reversal Models in Artificial Spin Ice
• Coupling-dependent antiferromagnetic-ferromagnetic ordering in a pinwheel artificial spin ice