FeNi-based magnetoimpedance multilayers: Tailoring of the softness by magnetic spacers

The microstructure and magnetic properties of sputtered permalloy films and FeNi(170 nm)/X/FeNi(170 nm) (X=Co, Fe, Gd, Gd-Co) sandwiches were studied. Laminating of the thick FeNi film with various spacers was done in order to control the magnetic softness of FeNi-based multilayers. In contrast to the Co and Fe spacers, Gd and Gd-Co magnetic spacers improved the softness of the FeNi/X/FeNi sandwiches. The magnetoimpedance responses were measured for [FeNi/Ti(6 nm)] 2/FeNi and [FeNi/Gd(2 nm)] 2/FeNi multilayers in a frequency range of 1-500 MHz: for all frequencies under consideration the highest magnetoimpedance variation was observed for [FeNi/Gd(2 nm)] 2/FeNi multilayers. © 2012 American Institute of Physics

Multi-Step Magnetization Process of Gd-Co/Co/Cu/Co Thermo-Sensitive Spin Valves

Magnetic and magnetoresistive properties of the Gd-Co/Co/Cu/Co magnetic type multilayered sensitive spin valve were studied as a function of temperature. It is shown that the appearance of a non-collinear magnetic structure significantly affects the shape of the magnetoresistive hysteresis loop. The characteristic values of the critical field related to the appearance of non-collinear structure depend on the temperature of the spin valve. The obtained results can serve as a basis for the improvements of functional properties and expanding the application areas of magnetic multilayered sensitive elements of the spin valve type; for example, for precise determination of the position of the object.This work was in part supported by RFBR grant 17-02-00236-a of Russian Federation and by the ACTIMAT ELKARTEK KK-2016/00097 grant of the Basque Country Government

Structural and magnetic characteristics of the Co/Cu/Co thin-film systems

The results on investigation of structural and magnetic characteristics of Co/Cu/Co thin-film systems obtained by magnetron sputtering on glass substrates are presented. The thickness of Co layers in all samples is equal to 5 nm and the Cu layer is varied from 0.5 to 4 nm. It is found that the saturation field, H S , oscillates in magnitude with increasing Cu layer thickness with the period of the order of 1 nm. The maximum values of H S are observed for t Cu = 1.4, 2.2 and 3.2 nm. The hysteresis loops measured for these samples in a magnetic field applied along the easy magnetization axis have a two-step form, and for other t Cu -rectangular one. The obtained results are explained by the presence of exchange coupling between the ferromagnetic layers through a Co spacer and its oscillating behavior with changing t Cu . © 2018 The Authors, published by EDP Sciences.This work was supported by the Russian Foundation of Basic Research, Grants 15-02-02077

Nanostructured giant magneto-impedance multilayers deposited onto flexible substrates for low pressure sensing

Nanostructured FeNi-based multilayers are very suitable for use as magnetic sensors using the giant magneto-impedance effect. New fields of application can be opened with these materials deposited onto flexible substrates. In this work, we compare the performance of samples prepared onto a rigid glass substrate and onto a cyclo olefin copolymer flexible one. Although a significant reduction of the field sensitivity is found due to the increased effect of the stresses generated during preparation, the results are still satisfactory for use as magnetic field sensors in special applications. Moreover, we take advantage of the flexible nature of the substrate to evaluate the pressure dependence of the giant magneto-impedance effect. Sensitivities up to 1 Ω/Pa are found for pressures in the range of 0 to 1 Pa, demostrating the suitability of these nanostructured materials deposited onto flexible substrates to build sensitive pressure sensors

Giant magnetoimpedance of FeNi-based nanostructures deposited onto glass and flexible substrates

This work was supported in part by the Basque Government through the Actimat Project under Grant IE13-380

Angular dependence of the ferromagnetic resonance parameters of [Ti/FeNi]6/Ti/Cu/Ti/[FeNi/Ti]6 nanostructured multilayered elements in the wide frequency range

Magnetically soft [Ti(6)/FeNi(50)]6/Ti(6)/Cu(500)/Ti(6)/[FeNi(50)/Ti(6)]6 nanostructured multilayered elements were deposited by rf-sputtering technique in the shape of elongated stripes. The easy magnetization axis was oriented along the short size of the stripe using deposition in the external magnetic field. Such configuration is important for the development of small magnetic field sensors employing giant magnetoimpedance effect (GMI) for different applications. Microwave absorption of electromagnetic radiation was experimentally and theoretically studied in order to provide an as complete as possible high frequency characterization. The conductor-backed coplanar line was used for microwave properties investigation. The medialization for the precession of the magnetization vector in the uniformly magnetized GMI element was done on the basis of the Landau–Lifshitz equation with a dissipative Bloch–Bloembergen term. We applied the method of the complex amplitude for the analysis of the rotation of the ferromagnetic GMI element in the external magnetic field. The calculated and experimental dependences for the amplitudes of the imaginary part of the magnetic susceptibility tensor x-component and magnetoabsorption related to different angles show a good agreement. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 18-19-00090Funding: This research was funded by the Russian Science Foundation, grant number 18-19-00090

Exchange Bias in FeMn/M (M = FeNi, Gd, Tb) Films

AbstractMicrostructure and hysteretic properties of magnetic multilayers were studied for Fe50Mn50/M structures, where M = Fe19Ni81, Gd or Tb. Comparative analysis of the hysteresis loops measured for the temperature range 5÷350K showed that Gd is not involved in the interlayer exchange coupling with antiferromagnetic Fe50Mn50 layer, while in the case of Tb definite indications of such interaction were observed. It is assumed that a qualitative difference in the magnetic behavior of these rare earth layers can be caused by differences in their structural features

Ferromagnetic resonance in FeCoNi electroplated wires

[EN] We have investigated the microwave properties (ferromagnetic resonance and ferromagnetic antiresonance) of FeCoNi magnetic tubes created by electroplating on CuBe wire. Important parameters such as the g factor, magnetization, anisotropy field, and damping parameter were obtained from the measurements. One sample, prepared by a method which entails rf-sputtering deposition of an additional FeNi layer, shows a clear ferromagnetic antiresonance. (C) 2003 American Institute of Physics.This work was partially supported by Spanish Secretaria de Estado de Educación y Universidades, Generalitat Valenciana under Project No. CTIDIA/2002/50, Spanish CICyT under Grant No. MAT2000-1047, Award No. Rec-005 of the U.S. Civilian Research and Development Foundation for the Independent States of the Former Soviet Union (CRDF). One of the authors (G.V.K.) thanks Spanish MCyT for her Ramon and Cajal Fellowship. The authors thank Professor V. O. Vas kovskiy for his help.García Miquel, ÁH.; Bhagat, S.; Lofland, S.; Kurlyandskaya, G.; Svalov, A. (2003). Ferromagnetic resonance in FeCoNi electroplated wires. Journal of Applied Physics. 94(3):1868-1872. https://doi.org/10.1063/1.1590407S18681872943Sixtus, K. J., & Tonks, L. (1932). Propagation of Large Barkhausen Discontinuities. II. Physical Review, 42(3), 419-435. doi:10.1103/physrev.42.419Panina, L. V., & Mohri, K. (1994). Magneto‐impedance effect in amorphous wires. Applied Physics Letters, 65(9), 1189-1191. doi:10.1063/1.112104Vázquez, M., & Hernando, A. (1996). A soft magnetic wire for sensor applications. Journal of Physics D: Applied Physics, 29(4), 939-949. doi:10.1088/0022-3727/29/4/001Britel, M. R., Ménard, D., Melo, L. G., Ciureanu, P., Yelon, A., Cochrane, R. W., … Cornut, B. (2000). Magnetoimpedance measurements of ferromagnetic resonance and antiresonance. Applied Physics Letters, 77(17), 2737-2739. doi:10.1063/1.1320042Garcı́a-Miquel, H., Garcı́a, J. ., Garcı́a-Beneytez, J. ., & Vázquez, M. (2001). Surface magnetic anisotropy in glass-coated amorphous microwires as determined from ferromagnetic resonance measurements. Journal of Magnetism and Magnetic Materials, 231(1), 38-44. doi:10.1016/s0304-8853(01)00040-3Wiggins, J., Srikanth, H., Wang, K.-Y., Spinu, L., & Tang, J. (2000). Magneto-impedance of glass-coated Fe–Ni–Cu microwires. Journal of Applied Physics, 87(9), 4810-4812. doi:10.1063/1.373167Pirota, K. ., Kraus, L., Chiriac, H., & Knobel, M. (2000). Magnetic properties and giant magnetoimpedance in a CoFeSiB glass-covered microwire. Journal of Magnetism and Magnetic Materials, 221(3), L243-L247. doi:10.1016/s0304-8853(00)00554-0Antonov, A. S., Buznikov, N. A., Iakubov, I. T., Lagarkov, A. N., & Rakhmanov, A. L. (2001). Nonlinear magnetization reversal of Co-based amorphous microwires induced by an ac current. Journal of Physics D: Applied Physics, 34(5), 752-757. doi:10.1088/0022-3727/34/5/314Gay-Balmaz, P., Maccio, C., & Martin, O. J. F. (2002). Microwire arrays with plasmonic response at microwave frequencies. Applied Physics Letters, 81(15), 2896-2898. doi:10.1063/1.1513663Beach, R. S., Smith, N., Platt, C. L., Jeffers, F., & Berkowitz, A. E. (1996). Magneto‐impedance effect in NiFe plated wire. Applied Physics Letters, 68(19), 2753-2755. doi:10.1063/1.115587Kurlyandskaya, G. V., Barandiarán, J. M., Gutiérrez, J., Garcı́a, D., Vázquez, M., & Vas’kovskiy, V. O. (1999). Magnetoimpedance effect in CoFeNi plated wire with ac field annealing destabilized domain structure. Journal of Applied Physics, 85(8), 5438-5440. doi:10.1063/1.369968Garcia, J. ., Asenjo, A., Sinnecker, J. ., & Vazquez, M. (2000). Correlation between GMI effect and domain structure in electrodeposited Co–P tubes. Journal of Magnetism and Magnetic Materials, 215-216, 352-354. doi:10.1016/s0304-8853(00)00156-6Yu, R. H., Landry, G., Li, Y. F., Basu, S., & Xiao, J. Q. (2000). Magneto-impedance effect in soft magnetic tubes. Journal of Applied Physics, 87(9), 4807-4809. doi:10.1063/1.373166Kurlyandskaya, G. ., Garcı́a-Miquel, H., Vázquez, M., Svalov, A. ., & Vas’kovskiy, V. . (2002). Longitudinal magnetic bistability of electroplated wires. Journal of Magnetism and Magnetic Materials, 249(1-2), 34-38. doi:10.1016/s0304-8853(02)00500-0Kurlyandskaya, G. V., Yakabchuk, H., Kisker, E., Bebenin, N. G., Garcı́a-Miquel, H., Vázquez, M., & Vas’kovskiy, V. O. (2001). Very large magnetoimpedance effect in FeCoNi ferromagnetic tubes with high order magnetic anisotropy. Journal of Applied Physics, 90(12), 6280-6286. doi:10.1063/1.1418423Favieres, C., Aroca, C., Sánchez, M. C., & Madurga, V. (2000). Matteucci effect as exhibited by cylindrical CoP amorphous multilayers. Journal of Applied Physics, 87(4), 1889-1898. doi:10.1063/1.372109Lofland, S. E., Garcia-Miquel, H., Vazquez, M., & Bhagat, S. M. (2002). Microwave magnetoabsorption in glass-coated amorphous microwires with radii close to skin depth. Journal of Applied Physics, 92(4), 2058-2063. doi:10.1063/1.149484

Features of the magnetic properties of Co/Si/Co thin-film systems

The magnetic properties of Co/Si/Co thin-film structures grown by magnetron sputtering have been studied using magnetooptical techniques. It is established that the saturation field (H S) of trilayers exhibits oscillations as a function of the thickness of the semiconductor (silicon) interlayer. This behavior is explained by structural features of the Co/Si/Co system and the presence of antiferromagnetic exchange coupling between magnetic layers via the silicon interlayer. © 2013 Pleiades Publishing, Ltd

Structural and magnetic properties of Ni0.8Fe0.2/Ti nanoscale multilayers

The influence of the thickness of the Ni0.8Fe0.2 (Permalloy, Py) layers on the structural and magnetic properties of magnetron sputtered Py/Ti multilayers was studied. The thickness of the Py layers was varied in the interval of 8 to 30 Å. X-ray reflectivity scans evidence the existence of a well-defined layered structure in all the samples considered, but also the presence of a complex intermixed interface. The shape of both the temperature dependence of magnetization and the hysteresis loops of the multilayered structures depends strongly on Py thickness. Magnetic and reflectivity measurements were comparatively analyzed in order to better understand the structure of the samples, and specifically, their interfaces. In particular, the presence of small superparamagnetic Py at the interfaces of the samples, especially evident in the samples with the thinnest Py layers, seems confirmed by the magnetic measurements, agreeing well with the reflectivity results. © 2018 by the authors.1 Instituto Regional de Investigación Científica Aplicada (IRICA) and Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain; [email protected] (J.A.G.); [email protected] (J.P.A.) 2 Department of Solid State Magnetism, Institute of Natural Sciences and Mathematics, Ural Federal University, 620002 Ekaterinburg, Russia; [email protected] (A.V.S.); [email protected] (G.V.K.) 3 Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao, SpainFunding: The research was supported by the Ministry of Education and Science of the Russian Federation (Agreement no. 02.A03.21.0006) and by the Spanish projects MAT2014-58034-R (MINECO/AEI/FEDER, EU) and PEII-2014-042-P (JCCM/FEDER, EU)