Magnetic Microwires: A Magneto-Optical Study

236 Pages·2014·8.055 MB·English

by  Alexander Chizhik, Julian Gonzalez

“This book is written by internationally recognized authors in materials science and provides an
excellent overview of the most important properties of microwires studied by the magneto-optical
technique. This is a promising book on the subject and is of interest to a large number of students and
M
researchers worldwide and across several disciplines.”
Prof. Alexander B. Granovsky a
M. V. Lomonosov Moscow State University, Russia g
n
“This book represents a crucial report on magnetic, optical, electric, and mechanical properties
e
of magnetic wires and glass-coated microwires from both fundamental and technological points of
t
view. The research is based on the magneto-optical techniques in which the authors are well-known i
experts.” c

Prof. Blanca Hernando M
University of Oviedo, Spain Alexander Chizhik | Julian Gonzalez
i
c
“This book presents extensive magneto-optical studies of magnetic microwires in a wide range of r
diameters from 0.5 to 120 μm. The authors show how magneto-optical studies can be employed for o
static and dynamic measurements of the domain structure in a cylindrical material covered by glass. w
A wide range of microwires are employed in the study.”
i
r
Dr. Rastislav Varga
e
Pavol Jozef Šafárik University in Košice, Slovakia
s
This book provides a comprehensive overview of the magneto-optical investigation of
cylindrically shaped magnetic microwires. The idea of studying magnetic wires using the
magneto-optic technique appeared in the late nineties of the 20th century as a response to the
discovery of the giant magneto-impedance effect—one of the most promising effects observed
in magnetic microwires.
The investigations have been performed on the intersection of the applied and basic sciences:
First, we sought the discovery of new effects. The next task was the optimization of the magnetic,
electrical, and mechanical properties of the wires taking into account the technological
application.
Alexander Chizhik received his PhD in 1991 from the B. Verkin Institute for Low
Temperature Physics and Engineering of the National Academy of Sciences of
Ukraine. For about 20 years, he was employed in this institute. Since 2002, he is
C
with the University of the Basque Country, San Sebastian, Spain. Prof. Chizhik
h
devoted the recent years to the magneto-optical investigations of magnetic i
z
microwires. As a pioneer in this scientific area, he created the original line of h
magneto-optics of cylindrically shaped objects. ik

|
Julian Gonzalez received his PhD from the University of the Basque Country
G
in 1987. At present, he is professor of applied physics in the Department of
o
Materials Physics of the university. Prof. Gonzalez’s research interest is very n
broad and covers materials physics, nanotechnology, and novel materials; z
a
magnetic sensors; magneto-elastic effects; magneto-transport phenomena, l
e
which include magneto-resistance, magneto-impedance at high frequency,
z
and ferromagnetic resonance; metamaterials at the gigahertz range; spintronic,
magneto-caloric, and shape magnetic memory materials; and micromagnetic
modeling and simulation.
V345
ISBN 978-981-4411-25-7
Magnetic
Microwires

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Alexander Chizhik | Julian Gonzalez
Magnetic
Microwires
editors A Magneto-
PrebenMaegaard
AnnaKrenz
WolfgaOngPalpz tical Study
The Rise of Modern Wind Energy
Wind Power
for the World
CRC Press
Taylor & Francis Group
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© 2013 by Taylor & Francis Group, LLC
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Version Date: 20140107
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Contents
Preface
ix
1. Kerr Effect as Method of Investigation of Magnetization
Reversal in Magnetic Wires 1
1.1 Introduction 1
1.2 MOKE Magnetometer (Loop Tracer) 2
1.3 MOKE Polarizing Microscopy 3
2. Cold-Drawn Fe-Rich Amorphous Wire 11
1.4 MOKE-Modified Sixtus–Tonks Method 5
2.1 Introduction 11
2.2 Two Magnetic Phases in Cold-Drawn Fe-Rich
Amorphous Wire 12
3. 2Co.3n veHnetliiocnaal lM Caog-Rniecthic A Smtrourcpthuoreu s Wire 1275
3.1 Introduction 25
3.2 Magnetization Reversal in Circular and Axial
Magnetic Fields 26
3.3 Model of Surface Magnetization Reversal 29
3.4 Effect of a Thermal Treatment 35
3.5 As-Quenched Wire 35
3.6 Annealed Wire 38
3.7 Torsion-Annealed Wire 40
3.8 Correlation between Switching Field and
Wire Length 41
3.9 Vortex-Type Domain Structure 45
vi Contents
4. Interaction between Glass-Covered Microwires 51
4.1 Introduction 51
4.2 Fe-Rich Microwires 52
5. Circular Magnetic Bistability in Co-Rich Amorphous
4.3 Co-Rich Microwires 56
Microwires 65
5.1 Introduction 65
5.2 Circular Magnetic Bistability Effect Related
with a Large Circular Barkhausen Jump 66
5.3 Circular Magnetic Bistability Induced by
Tensile Stress 71
5.4 Domain Structure in Glass-Covered Co-Rich
6. Effect of High-Frequency Driving Current on Magnetization
Microwires in Presence of Tensile Stress 77
Reversal in Co-Rich Amorphous Microwires 81
6.1 Introduction 81
6.2 Experimental Details 82
6.3 Surface Magnetization Reversal in Axial
Magnetic Field 83
6.4 Surface Magnetization Reversal in Circular
7. Relation between Surface Magnetization Reversal and
Magnetic Field 89
Magnetoimpedance 97
7.1 Introduction 97
7.2 Optimization of Giant Magnetoimpedance
in Co-Rich Amorphous Microwires 98
7.3 Circular Surface Magnetization Reversal
and Magnetoimpedance 101
7.4 Axial Surface Magnetization Reversal and
Magnetoimpedance 105
7.5 Correlation of Surface Domain Structure
8. Helicaaln Md aMgangentiect Sotirmupcteudraen ce 111119
8.1 Introduction 119
Contents vii
8.2 Magneto-Optical Determination of Helical
Magnetic Structure 119
8.3 Transverse Kerr Effect Dependencies 123
8.4 Helical Magnetic Structure in Microwires with
Different Value of Geometric Ratio 126
8.5 Surface and Bulk Magnetic Hysteresis Loops
of Co-Rich Glass–Covered Microwires 131
8.6 Experimental Determination of Limit Angle of
Helical Anisotropy in Amorphous Magnetic
Microwires 135
8.7 Correlation of Magnetic Behavior with Diameter
of Microwire 139
8.8 Magnetic Domain Structure Studied by Bitter
9. MagnTeetcizhantiioqnu eR eversal in Crossed Magnetic Field 114439
10. Visualization of Barkhausen Jump 157
10.1 Introduction 157
10.2 Experiment 158
11. 1M0a.3g nCeatilzcautliaotnio Rne versal in Glass-Covered Nano-Wires of 164
Cylindrical Shape 169
12. Magnetic Domain Wall Dynamics in Co-Rich Glass-Covered
Microwires 177
12.1 Introduction 177
12.2 Experiment 178
12.3 Comparison of Induction and MOKE Methods 178
13. Nucleation and Transformation of Circular Magnetic Domain
12.4 Domain Walls Dynamics in Co-Rich Microwires 180
Structure: Control of Domain Nucleation 189
13.1 Introduction 189
13.2 Circular Field–Induced Nucleation and
Transformation of Circular Magnetic Domains 189
13.3 Control of Domain Nucleation 194
viii Contents
14. Magnetization Reversal in Co-Rich Microwires with Different
Values of Magnetostriction 201
14.1 Introduction 201
15. Application of Magneto-Optical Indicator Film Method to
14.2 Experimental Results and Discussions 201
Study Domain Magnetic Structure in Microwires 207
15.1 Introduction 207
15.2 Experiment 208
I nde1x5 .3 Experimental Results and Discussion 209
215
Preface
The idea of studying magnetic wires using the magneto-optic
technique appeared in the late nineties of the 20th century as a
response to the discovery of the giant magneto-impedance (GMI)
effect—one of the most promising effects observed in magnetic
wires. This idea looked very attractive because of the following
reasons. The systematic magneto-optical investigation of the no-
plane objects had not been performed ever before. Usually the
magneto-optical technique is used to study plane objects, and the
present task of the magneto-optical investigation of cylindrically
shaped samples attracted me by unusual and original experimental
configuration. By that time I had acquired a good enough
background as an experimentalist in magneto-optics, obtained
in the well-known magneto-optical school belonging to the B.
Verkin Institute for Low Temperature Physics and Engineering in
Kharkov, Ukraine, and with 20 years of joint work with such great
scientists as academicians V. V. Eremenko, N. F. Kharchenko, and
S. L. Gnatchenko, who have taught me to always search the original
promising scientific tasks.

Another motivation was determined by the “surface” nature of

the GMI effect—the penetration depth of the accurrent changes in
the presence of dc applied magnetic field. As it is known, the
magneto-optical Kerr effect, which is usually used for the investiga-
tion of non-transparent objects, is also the “surface” effect—the
light reflected from the sample contains the information about
the magnetic behaviour in the thin near surface layer. In this way,
the task of obtaining a deep understanding of the surface
magnetization processes that affect the skin effect in magnetic
conductors has found a suitable powerful method.
It is necessary to remark that the great variety of the chemical
composition, sizes, and geometric ratios (metallic nucleus)/(glass
shell) promises a wide range of interesting magnetic effects to be
studied.