Crossover from superspin glass to superferromagnet in FexAg100-x nanostructured thin films ( 20 ≤ x ≤ 50 )

FexAg100?x granular thin films, with 20 x 50, have been prepared by the dc-magnetron sputtering deposition technique. With this technique we have been able to obtain samples comprising small Fe nanoparticles 2.5?3 nm embedded in a Ag matrix, remaining their size practically constant with increasing Fe content. Their magnetic behavior has been fully characterized by dc magnetic measurements between 5?350 K. They have revealed a crossover in the collective magnetic behavior of the Fe nanoparticles around a 35 at. %. Below such a concentration, a collective freezing of the magnetic moments is observed at low temperatures, while at high temperatures a transition, mainly mediated by dipolar interactions, to a magnetically disordered state is obtained. Above this concentration, direct exchange interactions overcome the dipolar magnetic interactions and a long-range order tends to prevail in the range of temperatures analyzed. ac magnetic measurements have indicated a crossover from a superspin glass x35 to a superferromagnetic x35 behavior for the magnetic moments of the Fe nanoparticles.This work was supported by the CICYT of Spain under Contracts No. MAT2008-06542-C04-02 and No. MAT2008- 06542-C04-04. SGIker technical support MEC, GV/EJ, European Social Fund is gratefully acknowledged. The financial support from the Basque Government Department of Education Project No. IT-347-07 is acknowledged

MAGNETIC HYSTERESIS PROPERTIES OF Tb-Co MULTILAYERED FILMS

The hysteresis properties of [Tb-Co/Ti]n and [Tb-Co/Si]n multilayered films were studied. The value of the coercive force and its temperature dependence strongly change with a de-crease of the Tb-Co layer thickness.This study was supported by the Ministry of Science and Higher Education of the Russian Federation (project No. FEUZ-2020-0051)

Magnetocaloric effect in TbCo-based multilayers

TbCo-based magnetic multilayers with different thicknesses of Tb-Co layers and non-magnetic spacers (Ti, Si) have been prepared by sputtering. The structure and magnetocaloric properties of these samples have been investigated. The peak value of magnetic entropy change in TbCo-based multilayers is smaller than the one previously reported for bulk counterparts. Nanostructuring leads to a table-like temperature dependence of the magnetic entropy change. It has been shown that the material of non-magnetic spacers can have a noticeable effect on magnetocaloric properties of TbCo-based magnetic multilayers. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 17-02-00236-aELKARTEK ACTIMAT-3 (2018-19) KK-2018/00099This work was supported by RFBR grant 17-02-00236-a of Russian Federation and by ELKARTEK ACTIMAT-3 (2018-19) KK-2018/00099 grant of the Basque Country Government

Magnetic Properties of FeNi Films Deposited by Oblique Sputtering at Different Growth Conditions

The role of the growth parameters in the formation of the magnetic anisotropy, domain structure and magnetization reversal of FeNi films was investigated. The conditions for thin films deposition with both maximum and minimum induced inplane uniaxial magnetic anisotropy are determined.This work was financially supported by the Russian Science Foundation (RSF), project No. 22-29-00980

Advanced Characterization of FeNi-Based Films for the Development of Magnetic Field Sensors with Tailored Functional Parameters

Magnetometry and ferromagnetic resonance are used to quantitatively study magnetic anisotropy with an easy axis both in the film plane and perpendicular to it. In the study of single-layer and multilayer permalloy films, it is demonstrated that these methods make it possible not only to investigate the average field of perpendicular and in-plane anisotropy, but also to characterize their inhomogeneity. It is shown that the quantitative data from direct integral and local measurements of magnetic anisotropy are consistent with the direct and indirect estimates based on processing of the magnetization curves. The possibility of estimating the perpendicular magnetic anisotropy constant from the width of stripe domains in a film in the transcritical state is demonstrated. The average in-plane magnetic anisotropy field of permalloy films prepared by magnetron sputtering onto a Corning glass is almost unchanged with the thickness of a single-layer film. The inhomogeneity of the perpendicular anisotropy field for a 500 nm film is greater than that for a 100 nm film, and for a multilayer film with a total permalloy thickness of 500 nm, it is greater than that for a homogeneous film of the same thickness. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 22-29-00980Funding: This research was funded by the Russian Science Foundation (RSF), project no. 22-29-00980, https://rscf.ru/en/project/22-29-00980/ (accessed on 20 March 2022)

Magnetic Properties of FeNi/Cu-Based Lithographic Rectangular Multilayered Elements for Magnetoimpedance Applications

The rectangular elements in magnetoimpedance (MI) configuration with a specific nanocomposite laminated structure based on FeNi and Cu layers were prepared by lift-off lithographic process. The properties of such elements are controlled by their shape, the anisotropy induced during the deposition, and by effects associated with the composite structure. The characterizations of static and dynamic properties, including MI measurements, show that these elements are promising for sensor applications. We have shown that competition between the shape anisotropy and the in-plane induced anisotropy of the element material is worth taking into account in order to understand the magnetic behavior of multilayered rectangular stripes. A possibility of the dynamic methods (ferromagnetic and spin-wave resonance) to describe laminated planar elements having a non-periodic modulation of both structure and magnetic parameters of a system is demonstrated. We show that the multilayered structure, which was originally designed to prevent the development of a “transcritical” state in magnetic layers and to reach the required thickness, also induces the effects that hinder the achievement of the goal, namely an increase in the perpendicular magnetic anisotropy energy. © 2023 by the authors.Russian Science Foundation, RSF: 22-29-00980This research was funded by the Russian Science Foundation (RSF), project no. 22-29-00980, https://rscf.ru/project/22-29-00980/ (accessed on 1 July 2023)

Dynamics of lactate as an indicator of postoperative complications

The article is devoted to a comparative analysis of blood lactate readings during heart surgery in newborns and to identifying the dependence of the dynamics of lactate on the further condition of patients.Статья посвящена сравнительному анализу показаний лактата крови при операциях на сердце у новорожденных детей и выявлению зависимости динамики лактата на дальнейшее состояние пациенто