Fig. 6: The magnetization reversal study of Ammann artificial magnetic quasicrystals (AMQs) using X-ray photoemission electron microscopy (XPEEM).
XPEEM topography image for Ammann tilings (a) ATA (μ0H = 34 mT), (b) ATB (at 47 mT), and (c) ATC (at 47 mT) representing the switching of 47%, 47%, and 53% Type I nanobars. Bright (dark) regions correspond to magnetic (non-magnetic) regions. The scale bar corresponds to 1 μm. The arrow represents the field direction. The X-ray direction was misaligned by 22° to optimize the detection of nanobars of all the different orientations. d–f X-ray magnetic circular dichroism (XMCD) data of topography images shown in (a)–(c). Blue (red) colors represent magnetization parallel (opposite) to the X-ray direction. Blue color indicates a reversed nanobar. Notice the weak contrast of nanobars whose orientation deviates from the X-ray direction. The magnetic configurations of Ammann tilings in the as-grown state are displayed in Supplementary Fig. 2. g–i Charge model (CM) analysis of XMCD experimental data shown in (d)–(f). The green and orange filled circles at the vertices represent positive and negative vertex charges, respectively. Here the circles with smallest and largest diameter and intensity represent charge ∣Q∣ = 0 and ∣Q∣ = 5, respectively. j–l Classification of reversal in terms of switching of Type I and II of nanobars for ATA, ATB, and ATC, respectively. Legends I and II represent nanobars of Types I and II. m–o Total charge count for ATA, ATB, and ATC, respectively. p–r Number of clockwise (CW) and counter-clockwise (CCW) flux-closure loops (FCLs) (see the inset in (p) for their definition) for ATA, ATB, and ATC, respectively. s–u Charge depiction for ATA, ATB, and ATC, respectively. The purple, dark yellow, and dark cyan colored symbols represent charges 3 (N = 3), 4 (N = 4), and 5 (N = 5), respectively. The error bars are calculated based on the number of nano bars below the noise level of the background (that is, the signal-to-noise ratio is below 1). The error bars in Fig. 5p, q are multiplied by five times for better comparison purposes.
