Effect of Magnetic Field on the Morphology and Structural Characteristics of Cobalt-based Thin Film Systems as Sensitive Sensor Elements

Authors I. Shpetnyy1, 2 , T. Plecenik2, Yu. Shabelnyk1, Yu. Shkurdoda1, U. Shvets1, I. Nakonechna1, S. Vorobiov3, A. Kravets4
Affiliations

1 Sumy State University, 2, Rimsky-Korsakov St, 40007 Sumy, Ukraine

2 Faculty of Mathematics, Physics and Informatics, Comenius University Bratislava, Mlynska dolina F2, 84248 Bratislava, Slovakia

3 Institute of Physics, Faculty of Science, P.J. Šafárik University, Park Angelinum 9, 04013 Košice, Slovakia

4 Institute of Magnetism, National Academy of Sciences of Ukraine, Ministry of Education and Science of Ukraine, Academician Vernadsky Blvd. 36-b, 03142 Kyiv, Ukraine

Е-mail i.shpetnyi@aph.sumdu.edu.ua
Issue Volume 15, Year 2023, Number 4
Dates Received 25 May 2023; revised manuscript received 21 August 2023; published online 30 August 2023
Citation I. Shpetnyy1,2, T. Plecenik, et al., J. Nano- Electron. Phys. 15 №4, 04034 (2023)
DOI https://doi.org/10.21272/jnep.15(4).04034
PACS Number(s) 75.47.De, 75.70.Cn
Keywords Sensor (27) , Giant magnetoresistance, Granular thin films, Spin-dependent scattering, Electron beam evapora-tion, Co-evaporated technique, Magnetic aftereffect phenomenon.
Annotation

This work presents the results of a study of the influence of an external magnetic field on the surface morphology of three different thin-film magnetic structures were presented: a single-layer Co film, a granular film alloy based on Co and Ag, and a trilayer Co/Gd/Co film. Atomic force microscopy investigations at room temperature revealed a significant influence of the magnetic field on the surface morphology of the films and their structural characteristics (arithmetic mean Ra, root mean square Rq, structural entropy S). After the initial application of the magnetic field (at H = 0.01 T), a decrease in the surface roughness (Ra, Rq) was observed for all systems, which is associated with the destruction of the system of defects in the film samples and the transition of the structure to a new, more stable state. The most substantial reduction in roughness, with Ra decreasing by 19% and Rq by 16 %, was observed in the granulated magnetic films based on Co and Ag. Further increases in the magnetic field practically had no effect on the structural characteristics, which remained constant even after relaxation over 18 hours. In the case of the single-layer Co films, with a subsequent increase in the magnetic field strength to 0.05 T, the values of structural characteristics (Ra, Rq, S) monotonously increased. Further intensification of the magnetic field to 0.1 T almost did not affect Ra, Rq, S. For the trilayer Co/Gd/Co film system, further increasing the magnetic field intensity to 0.1 T led to an increase in the roughness parameters Ra and Rq, due to additional stresses in the upper Co layer. This effect was a result of the lower coercive force in the bottom Co layer compared to the upper Co layer. As a result, the lower Co layer magnetized at lower magnetic fields compared to the upper layer, which further increased the roughness of the film's surface.

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