Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Nonlinear Electrоmagnetic Properties of Thinfilm Nanocomposites (CoFeZr)x(MgF2)100-x

Evelina Pavlovna Domashevskaya
* ORCID logo ,
Sergey Alexandrovich Ivkov
ORCID logo ,
Pavel Vladimirovich Seredin
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Dmitry Leonidovich Goloshchapov
,
Konstantin Alexandrovich Barkov
,
Stanislav Viktorovich Ryabtsev
,
Yrii Gavriilovich Segal
,
Alexander Victorovich Sitnikov
,
Elena Alexandrovna Ganshina
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Version 1 : Received: 28 April 2023 / Approved: 29 April 2023 / Online: 29 April 2023 (03:17:33 CEST)

A peer-reviewed article of this Preprint also exists.

Domashevskaya, E.P.; Ivkov, S.A.; Seredin, P.V.; Goloshchapov, D.L.; Barkov, K.A.; Ryabtsev, S.V.; Segal, Y.G.; Sitnikov, A.V.; Ganshina, E.A. Nonlinear Electrоmagnetic Properties of Thinfilm Nanocomposites (CoFeZr)x(MgF2)100−x. Magnetochemistry 2023, 9, 160. Domashevskaya, E.P.; Ivkov, S.A.; Seredin, P.V.; Goloshchapov, D.L.; Barkov, K.A.; Ryabtsev, S.V.; Segal, Y.G.; Sitnikov, A.V.; Ganshina, E.A. Nonlinear Electrоmagnetic Properties of Thinfilm Nanocomposites (CoFeZr)x(MgF2)100−x. Magnetochemistry 2023, 9, 160.

Abstract

The aim of this work is a comprehensive study of the effect of variable atomic composition and structural-phase state of (CoFeZr)x(MgF2)100-x nanocomposites (NCs) on their nonlinear electronic and magnetic/magneto-optical properties. Micrometer-thick nanocomposites layers on the glass substrates were obtained by ion-beam sputtering of a composite target in the argon atmosphere in a wide range of compositions x=9-51at.% The value of the resistive percolation threshold xper=34 at.%, determined from the concentration dependences of the electrical resistance of NCs, coincides with the beginning of nucleation of metallic nanocrystals CoFeZr in MgF2 dielectric matrix. The absolute value of maximum magnetoresistance of NCs is 2.4 % in a magnetic field of 5.5 kOe at x=25 at.%, up to the percolation threshold. Two maxima appear in the concentration dependences of magneto-optical transversal Kerr effect, one of which at x = 34 at.% corresponds to the formation of CoFeZr alloy nanocrystals of a hexagonal structure, and the second one at x=45 at.% corresponds to the phase transition of nanocrystals from a hexagonal to a cubic body-centered structure. The magnetic percolation threshold in (CoFeZr)x(MgF2)100-x system at xfm=34 at.% with the appearance of a hysteresis loop and a coercive force of Hc≈ 8 Oe, coincides with the resistive percolation threshold xper=34 at.%. Concentration dependence of the coercive force showed that at low contents of metallic alloy x<30 at.% NCs are superparamagnetic (Hc=0). With an increase of the alloy content, in the region of magnetic and resistive percolation thresholds NCs exhibit a magnetically soft ferromagnetic character and do not change it far beyond the percolation threshold with the maximum value of the coercive force Hc< 30 Oe. Decrease in magnetic order and soft ferromagnetic are influenced by the diamagnetic phase FeF2 that we discovered at the interface of magnetic nanocrystals CoFeZr with a dielectric matrix MgF2 by the Mössbauer spectroscopy.

Keywords

nanocomposites; nanocrystals; magnetoresistance; percolation threshold; magneto-optical properties; transversal Kerr effect; superparamagnetic; soft ferromagnetic

Subject

Physical Sciences, Condensed Matter Physics

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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