Citation: Gritsenko, C.; Lepalovskij,
V.; Volochaev, M.; Komanický, V.;
Gorkovenko, A.; Pazniak, H.; Gazda,
M.; Andreev, N.; Rodionova, V.
Complex Study of Magnetization
Reversal Mechanisms of FeNi/FeMn
Bilayers Depending on Growth
Conditions. Nanomaterials 2022, 12,
1178. https://doi.org/10.3390/
nano12071178
Academic Editors: Ki-Hyun Kim and
Deepak Kukkar
Received: 25 February 2022
Accepted: 28 March 2022
Published: 1 April 2022
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Article
Complex Study of Magnetization Reversal Mechanisms of
FeNi/FeMn Bilayers Depending on Growth Conditions
Christina Gritsenko
1,
*, Vladimir Lepalovskij
2
, Mikhail Volochaev
3
, Vladimir Komanický
4
,
Aleksandr Gorkovenko
2
, Hanna Pazniak
5
, Maria Gazda
6
, Nikolai Andreev
1,7
and Valeria Rodionova
1
1
Research and Education Center “Smart Materials and Biomedical Applications”, Immanuel Kant Baltic
Federal University, Gaidara str., 6, 236041 Kaliningrad, Russia; andreevn.misa@gmail.com (N.A.);
valeriarodionova@gmail.com (V.R.)
2
Solid State Magnetism Department, Institute of Natural Sciences and Mathematics, Ural Federal University,
620002 Yekaterinburg, Russia; vladimir.lepalovsky@urfu.ru (V.L.); a.n.gorkovenko@urfu.ru (A.G.)
3
Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50/38,
660036 Krasnoyarsk, Russia; volochaev91@mail.ru
4
Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9,
040 01 Kosice, Slovakia; vladimir.komanicky@upjs.sk
5
Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen,
47057 Duisburg, Germany; hanna.pazniak@uni-due.de
6
Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12,
80233 Gdansk, Poland; margazda@pg.edu.pl
7
Materials Science and Metallurgy Shared Use Research and Development Center, National University of
Science and Technology MISiS, 119049 Moscow, Russia
* Correspondence: christina.byrka@gmail.com; Tel.: +7-4012-595-595 (ext. 9103)
Abstract:
Magnetization reversal processes in the NiFe/FeMn exchange biased structures with
various antiferromagnetic layer thicknesses (0–50 nm) and glass substrate temperatures (
17–600
◦
C
)
during deposition were investigated in detail. Magnetic measurements were performed in the
temperature range from 80 K up to 300 K. Hysteresis loop asymmetry was found at temperatures
lower than 150 K for the samples with an antiferromagnetic layer thickness of more than 10 nm.
The average grain size of FeMn was found to increase with the AFM layer increase, and to decrease
with the substrate temperature increase. Hysteresis loop asymmetry was explained in terms of the
exchange spring model in the antiferromagnetic layer.
Keywords:
exchange bias; exchange spring; AFM grain size; substrate temperature; hysteresis loop
asymmetry; magnetization reversal
1. Introduction
For thin film materials with exchange-coupled ferro- (FM) and antiferromagnetic
(AFM) layers, below the Neel temperature and at the induced uniaxial anisotropy, magnetic
hysteresis loops are shifted. This phenomenon is called the exchange bias and is widely used
in modern spintronics, magnetic recording, and magnetic sensorics, for example, in giant
magnetoresistance (GMR)-based or giant magnetoimpedance (GMI)-based elements [
1
–
3
].
Depending on the application, the most important property of an exchange bias system
can be either the effect value [4], or layer thickness [2,5], or hysteresis loop shape [5–7].
Experimental studies show that the magnetic properties of an exchange bias system are
in the direct dependence on layer thickness, roughness, grain size, and deposition sequence [
8
].
The above characteristics of thin films prepared by magnetron sputtering can be varied by
changing the pressure or substrate temperature in the chamber during deposition [9,10].
Ni
80
Fe
20
alloy (Permalloy) is one of the most useful materials for exchange bias sys-
tems due to its high initial and maximum magnetic permeability, as well as corrosion
resistance, when compared with other materials. For using it in GMR sensors, an optimal
Nanomaterials 2022, 12, 1178. https://doi.org/10.3390/nano12071178 https://www.mdpi.com/journal/nanomaterials
