SPICE Workshop on Nanomagnetism in 3D, April 30th - May 2nd 2024
Sam Ladak
Three-dimensional (3D) magnetic nanostructures exhibit rich phenomena from topological spin texture stabilisation through nanoscale curvature [1], to novel ground states driven by 3D frustrated interactions [2-5]. I will start by providing a brief overview of work carried out at Cardiff, whereby two-photon lithography (TPL) has been used to realise and study 3D artificial spin-ice systems. I will then focus upon recent work whereby we have utilized a modified commercial TPL system and deposition to fabricate sub-100 nm 3D ferromagnetic nanowires with both cross-sectional and longitudinal curvature. Physical characterisation reveals lateral feature sizes down to 80 nm can be obtained directly from the TPL write, whilst micromagnetic simulations elucidate a range of novel domain wall configurations induced by the cross-sectional curvature of the system. Magnetic force microscopy characterisation in externally applied magnetic fields are used to directly visualise the injection and pinning of domain walls in these 3D magnetic nanowires. Using a simple model which considers only the local magnetostatic energy landscape, the domain wall pinning is shown to arise due to subtle variations in thickness and roughness across the nanowire.
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A. May et al. “Magnetic charge propagation upon a 3D artificial spin-ice”, Nature Communications 12, 3217 (2021)
Sahoo, S. et al. “Observation of Coherent Spin Waves in a Three-Dimensional Artificial Spin Ice Structure”, Nano Letters 21, 4629 (2021)
M. Saconne et al. “Exploring the phase diagram of 3D artificial spin-ice”, Communications Physics 6, 217 (2023)
E. Harding et al. “Imaging the magnetic nanowire cross section and magnetic ordering within a suspended 3D artificial spin-ice”, APL Materials 12, 021116 (2024)