The single power law relationship between coercivity and width in pointed composite element magnetic barcodes

• Published in: Journal of applied physics 2023-10, Vol.134 (13)
• Main Authors: Newton, P. J., Masur, S. M., Devlin, N. B., Ghidini, M., Backes, D., Maccherozzi, F., Pacheco-Pumaleque, A. A., Barnes, C. H. W.
• Format: Article
• Language: English
• Subjects: Bar codes; Coercivity; Dichroism; Emission microscopy; Kerr magnetooptical effect; Magnetization reversal; Power law
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0166821

Pointed magnetic elements are introduced as an improvement upon rectangular strips currently employed in composite element magnetic barcodes. The coercivity of these elements, as measured using the magneto-optic Kerr effect, is found to strictly adhere to a single power law relationship with the element width, where the power law exponent is dependent on the length of the pointed region and takes values between −0.98 and −0.91. The steeper gradients here, along with the absence of the crossover region seen in rectangular devices, present these structures as a strict improvement in terms of potential device applications. These improvements are found to be present for all structures where the pointed region is as long as, or longer than, the magnetic element is wide. The remanent magnetization configuration, imaged using photo-emission microscopy with contrast from x-ray magnetic circular dichroism (XMCD-PEEM), is compared to the results of micromagnetic simulations. It is found to cant inward in the pointed section of the strip, aligning with the edges of the point, pinning the magnetization and giving a consistent magnetization reversal behavior for all element widths investigated.