Magnetic barcodes containing 32 composite element bits have been produced and measured in order to optimize the design of magnetic microcarriers. Focused magneto-optic Kerr effect measurements allow the determination of the change in magnetic hysteresis when the width of magnetic elements is varied between bits, and the electron beam lithography used in production is confirmed to be accurate to ∼6 nm using scanning electron microscopy. The sharp magnetic switching observed, an important prerequisite for a functioning device, is attributed to the expected dipolar interactions between magnetic elements and the use of magnetically soft Permalloy. A crossover between two magnetic reversal behaviors is discovered when the magnetic elements are ∼200 nm wide. From these measurements, 12 bits were selected on which data can be written with a low probability of error, with the prospect of the other 20 bits being employed for error correction. We have therefore developed a nonvolatile magnetic memory on which 4096 unique codes can be programmed.
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14 October 2019
Research Article|
October 15 2019
The magnetic reversal characteristics of 32-bit composite element magnetic barcodes
P. J. Newton
;
P. J. Newton
a)
1
Department of Physics, Cavendish Laboratory, University of Cambridge
, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
a)Author to whom correspondence should be addressed: pjn32@cam.ac.uk
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L. De Los Santos Valladares
;
L. De Los Santos Valladares
1
Department of Physics, Cavendish Laboratory, University of Cambridge
, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
2
School of Materials Science and Engineering, Northeastern University
, No 11, Lane 3, Wenhua Road, Heping District, Shenyang 110819, People's Republic of China
3
Laboratorio de Superconductividad, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos
, Ap. Postal 14–0149, Lima 15081, Peru
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R. Celis Rojas;
R. Celis Rojas
4
Laboratorio de Celdas Solares, Universidad Nacional de Barranca, Av. Toribio de Luzuriaga N°376
, Mz J, Urbanización La Florida, Distrito y Provincia de Barranca 15169, Peru
5
Laboratorio de Ciencias, Universidad Nacional Autónoma de Tayacaja “Daniel Hernandez Morillo,”
Jr., Bolognesi 418, Pampas 09156, Huancavelica, Peru
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C. H. W. Barnes
C. H. W. Barnes
1
Department of Physics, Cavendish Laboratory, University of Cambridge
, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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a)Author to whom correspondence should be addressed: pjn32@cam.ac.uk
Appl. Phys. Lett. 115, 162404 (2019)
Article history
Received:
July 08 2019
Accepted:
October 04 2019
Citation
P. J. Newton, L. De Los Santos Valladares, R. Celis Rojas, C. H. W. Barnes; The magnetic reversal characteristics of 32-bit composite element magnetic barcodes. Appl. Phys. Lett. 14 October 2019; 115 (16): 162404. https://doi.org/10.1063/1.5119075
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