Magnetic Nano- and Microwires: Design, Synthesis, Properties and Applications

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Magnetic Nano- and
Microwires:
Design, Synthesis, Properties and
Applications
Copyright
Contributors
Preface
Part One: Design, synthesis, and properties
1
3D porous alumina: A controllable platform to tailor magnetic nanowires
	Introduction
	Modulated magnetic nanowires
		Magnetic nanowires with modulated diameter
		Composition modulation: Multilayered nanowires
		Relative orientation modulation: Radial nanowire array
	Magnetic structures with a 3D geometry
		Self-sustaining interconnected nanowire networks from ion-irradiated 3D polymeric templates
		3D nanostructures fabricated inside lithography patterned resists
		Self-sustaining interconnected nanowire network 3D structures from 3D AAO templates
			Fabrication process and morphological description of the structures
	Summary and outlook
	Acknowledgments
	References
2
Electrochemical methods assisted with ALD for the synthesis of nanowires
	Introduction
	Atomic layer deposition technique
	ALD on nanoporous templates: Tailored nanowire arrays
	Magnetic nanotubes
	Core-shell magnetic nanostructures
	Diameter modulated nanowires
		Magnetic properties of diameter modulated NiFe nanowire array
		Micromagnetic simulations of single Ni and NiFe bisegmented diameter modulated nanowires
		Magnetic properties of diameter modulated FeCo nanowires array
	Conclusions
	References
	Further reading
3
Intermetallic nanowires fabricated by metallic flux nanonucleation method (MFNN)
	Introduction
	Nanoporous alumina template synthesis: Hard anodization
	Crystal growth: Metallic flux and metallic flux nanonucleation (MFNN)
		Metallic flux method
		Metallic flux nanonucleation (MFNN) method
	Examples of intermetallic nanowires fabricated by MNFM
		Fe3G4 nanowires: An itinerant metamagnetic compound
		GdIn3: An intermetallic correlated electron system
		Ga: A type I like superconductor at low dimension
	Conclusions
	Acknowledgments
	References
4
Fabrication and magneto-optical characterization of 3D-printed permalloy nanowires
	Introduction
	3D-nanoprinted scaffolds for permalloy evaporation
	Magnetic functionalization of scaffolds through permalloy evaporation
	Dark-field magneto-optical Kerr effect (MOKE) magnetometry
	Characterization of 3D magnetic domain-wall motion using dark-field MOKE magnetometry
		Indirect probing of transmission barriers
	Controlling switching mechanism and domain-wall injection in a suspended 3D nanowire
	Summary and outlook
	Acknowledgments
	References
	Further reading
5
Growth of nanowire heterostructures and their optoelectronic and spintronic applications
	Introduction
	Synthesis
		Axial heterostructures
		Radial heterostructures
		Nanowire arrays
		Branched heterostructures
	Potential applications
		Multipole resonances in nanowires
		Optical applications: Structural colors, unidirectional scattering
			Unidirectional scattering
			Structural colors
		Optoelectronic applications
			LEDs
			Solar cells
			Hybrid NW heterostructures
		Spintronic applications
	Future issues and outlook
	Summary
	References
6
Cylindrical magnetic nanotubes: Synthesis, magnetism and applications
	Introduction
	Porous templates
		Polycarbonate membranes
		Nanoporous alumina membranes
	Electrochemical deposition of cylindrical nanotubes
		Electrochemical cell
		Annular-shaped working electrodes
		Activation of the pore walls
		Tuning of the deposition time
		Importance of the deposition potential
		Formation of hydrogen bubbles
		Electrochemical dealloying method
		Annular nanochannels
		3-D interconnected nanotube networks
	Other template-filling growth methods
		Atomic layer deposition
		Chemical vapor deposition
		Sol-gel method
		Wetting process
		Electroless plating
		Thermal oxidation of nanowires (Kirkendall effect)
		Electrochemical oxidation (anodization)
		Hydrothermal process
	Magnetism of cylindrical nanotubes
		Magnetic interactions
		Magnetization reversal
		Magnetic domain wall dynamics
		Exchange bias and thermal effects
	Applications of magnetic nanotubes
	Conclusions
	Acknowledgments
	References
7
From soft chemistry to 2D and 3D nanowire arrays with hard magnetic properties and permanent magnet applications
	Introduction
	Chemical synthesis of magnetic nanowires
		Polyol method
			General principles
			Morphology and structure
		Organometallic chemistry: Control of morphology of Co nanorods
			General principles
			Structure and formation mechanism of cobalt nanorods and nanowires
			Spontaneous formation of 3D arrays of Co nanorods in solution
	Optimization of the magnetic properties of individual wires
		Micromagnetic modeling
			Effect of the shape of elongated magnetic particles on the coercive field
			Mean diameter and aspect ratio
			Effect of stacking faults
		Comparison with experimental results
	2D arrays of Co nanorods combining epitaxy and organometallic chemistry
		Growth and structural characterizations of 2D nanorods arrays
		Magnetic properties of 2D arrays of perpendicular nanorods
	From nanowires to 3D bulk permanent magnets
		Magnetic properties of 3D assemblies of nanowires
			Influence of the degree of alignment
			Effect of dipolar interactions
			Influence of the packing density
		Dense arrays of parallel nanorods
		Consolidation of nanowires
	Conclusion
	References
	Further reading
8
Recent trends in magnetic nanowires and submicron wires prepared by the quenching and drawing technique
	Introduction
	Magnetic behavior
		Characterization methods
		Main aspects of the magnetic behavior
		Magnetostatic and magnetoelastic contributions
	Domain wall propagation
		Experimental techniques
		Domain wall velocity and mobility
		Shape of the propagating domain walls
		Controlled motion of domain walls
	Effects of structural transformations
	Final remarks and future work
	Acknowledgments
	References
9
Heusler-type glass-coated microwires: Fabrication, characterization, and properties
	Introduction
	Evaluation of applicability of glass-coated microwires for use in magnetocalorics
	Preparation of glass-coated microwires
	Experimental techniques used for characterization of Heusler-type microwires
	Magnetic, magnetotransport, and structural properties microwires from Heusler alloys
		Effect of annealing on magnetic properties of microwires from Heusler alloys
		Magnetoresistance
		Structure of Heusler-type microwires
	Magnetocaloric effect of Heusler-type microwires
	Magnetic hardening and exchange bias effect in Heusler-type microwires
	Conclusions
	Acknowledgments
	References
	Further reading
Part Two: Magnetization mechanisms, domains and domain walls
10
Current-induced dynamics of chiral domain walls in magnetic heterostructures
	Introduction
	The 1D model of domain walls
		Equation of motion
		Domain wall velocity
		Depinning threshold current
		Domain wall inertia
	Experimental results
		Sample preparation and experimental methods
		Spin-orbit torque
		Measurements of domain wall velocity
		Determination of the magnetic chirality
		Effective mass of chiral domain walls
		Synchronous motion of highly packed coupled chiral domain walls
	Conclusion
	Acknowledgments
	References
	Further reading
11
Joule heating and its role in current-assisted domain wall depinning in nanostrips
	Introduction
		General aspects for the thermal characterization of magnetic nanostrips
			The thermal conductivity
			Is the injected current pulse short enough?
			Thermal contact resistance
	Thermal behavior of a ferromagnetic nanostrip
	Fabrication of the nanostrips: Some considerations
	Micromagnetic model and modeling details
		Micromagnetic model at zero or finite uniform temperature
		Micromagnetic model and heat transport to account for the Joule effects
	Micromagnetic results
		Field- and current-driven DW dynamics at zero temperature
			Field-driven DW motion
			Current-driven DW motion
		DW nucleation by a current pulse along a bit line
		Current-assisted DW depinning from a notch
			Deterministic analysis in the absence of the Joule heating effect
			Current-assisted DW in the presence of Joule heating effect
	Conclusions
	Acknowledgments
	References
	Further reading
12
Controlling magnetism by interface engineering
	Introduction
		Perpendicular magnetic anisotropy
		The Dzyaloshinskii-Moriya interaction
		Magnetic domain walls
	E-field control of magnetism
		Physical mechanism and device geometries
		E-field control of PMA
		E-field control of magnetic DW motion
		E-field control of DMI
	He+ ion irradiation
		Modification of PMA and DMI by ion irradiation
		Magnetic domain wall motion and irradiation-induced disorder
	Conclusion and outlook
	References
13
Skyrmion lines, monopoles, and emergent electromagnetism in nanowires
	Introduction
	Skyrmion lines and monopoles in nanowires
	Emergent electromagnetic fields
	Other sample geometries and thermal fluctuations
	Conclusions
	References
14
Micromagnetic modeling of magnetic domain walls and domains in cylindrical nanowires
	Introduction
	Hysteresis loops of magnetic nanowires
	Magnetic domains and domain walls in straight magnetic nanowires
	Domain wall velocity in cylindrical magnetic nanowires
	Domains and domain walls in nanowires with geometrical modulations
	Domain walls and domains in multisegmented Co/Ni nanowires
	Conclusions
	References
15
Domain wall pinning in a circular cross-section wire with modulated diameter
	Introduction
		Fundamental and technological motivations for domain wall pinning
		Types of pinning for nanowires
		Existing theories and experiments
	Theoretical background
		Domain walls in cylindrical nanowires
		Geometry of modulation and potential barrier
		Magnetic charges
		Magnetic field generated by the modulation
		Energy of interaction
	Modulation under applied magnetic field
		Abrupt modulation
		Smooth modulation
		Protrusion: Double abrupt modulation
	Modulation under applied current
	Conclusion and perspective
	Acknowledgments
	References
16
Magnetic imaging of individual modulated cylindrical nanowires
	Introduction to the imaging techniques
	Synthesis and fabrication of modulated nanowires into the anodic aluminum oxide templates
		Diameter-modulated nanowires obtained by varying the anodization parameters
		Diameter-modulated nanowires obtained by pulsed anodization
	Magnetic characterization of nanowire arrays
	Magnetic characterization of individual nanowires with uniform diameter
	Study of geometrically modulated nanowires
	Multisegmented nanowires
	Remarks and conclusion
	Acknowledgments
	References
17
Determining magnetization configurations and reversal of individual magnetic nanotubes
	Introduction
		Magnetic nanostructures
		Ferromagnetic nanotubes
		Measuring assemblies versus individual magnetic nanotubes
	Magnetoresistance
	Torque magnetometry
	Magnetic imaging with X-rays
	Scanning SQUID microscopy
	Magnetic force microscopy
	Conclusions and outlook
	References
18
Helical magnetic structures in amorphous microwires: Magneto-optical study and micromagnetic simulations
	Introduction
	Magnetization reversal and domain structures
		Microwires compositions and experimental details
		Visualization of surface magnetic domain structures
		Imaging of the magnetization reversal by MOKE microscopy
	Elliptic domain structures
	Spiral domain structures
	Conclusions
	Acknowledgments
	References
	Further reading
19
On-time characterization of the dynamics of a single-domain wall in an amorphous microwire
	Introduction
	Sixtus and Tonks measurements
	Time-resolved measurement of the DW velocity
	Braking and trapping a single-domain wall
	Injection of domain walls
	Conclusions
	Acknowledgment
	References
20
Dynamical behavior of ferromagnetic nanowire arrays: From 1-D to 3-D
	Introduction
	High-frequency characterization techniques
		Fixed frequency (cavity-based) FMR spectroscopy
		Vector network analyzer-FMR spectroscopy
		Brillouin light scattering spectroscopy
		Time-resolved magneto-optical Kerr effect microscopy
	Nanowire arrays
		Fabrication of ferromagnetic nanowire arrays
			Fabrication of ferromagnetic nanowire arrays in polymeric etched ion-track templates
			Fabrication of ferromagnetic nanowire arrays in alumina templates
		Static properties of ferromagnetic nanowire arrays
	High-frequency behavior of ferromagnetic nanowire arrays
		Dynamical behavior of saturated isolated ferromagnetic nanowires
		Dynamical behavior of saturated ferromagnetic nanowire arrays
		Dynamical behavior of unsaturated ferromagnetic nanowire arrays
		Dynamical behavior of ferromagnetic nanowire arrays considering the magnetocrystalline anisotropy term
		Dynamical behavior of multilayer ferromagnetic nanowire arrays
		Dynamical behavior of gradient ferromagnetic nanowire arrays
	3-D nanowire arrays
		Fabrication of 3-D ferromagnetic nanowire arrays
		Static properties of 3-D ferromagnetic nanowire arrays
		High-frequency behavior of 3-D ferromagnetic nanowire arrays
	High-frequency applications and future perspectives of ferromagnetic nanowire arrays
	References
21
Spin waves and electromagnetic waves in magnetic nanowires
	Introduction
	From single magnetic nanowire to 2-D nanowire arrays
		Interactions in nanowire arrays
			Static magnetic properties of nanowires
			The role of shape anisotropy: Demagnetizing tensor of nonellipsoidal magnetic elements
			Static dipolar interaction effects in nanowire arrays
			Configurational phase transitions in arrays of nanowires
	Magnetic nanowires in electromagnetic fields
		SWs in magnetic nanowires
			Dipolar-exchange spin-wave modes of individual cylindrical nanowires
			Collective spin-wave modes in arrays of interacting nanowires
			Spin waves in ferromagnetic nanowires with noncircular cross section
			Magnetic structure and dynamics of multilayered nanowires and magnetic nanotubes
			Effects of curvature and torsion on the magnetic dynamics in nanowires and nanotubes
	Interactions of EMWs with nanowires
		EMW propagation in nanostructures
			EMW interactions with nanowire structures
			Shape and size effects in the EMW propagation in nanoarrays
			EMW scattering in nanowires at THz frequencies
		High-frequency applications of magnetic nanowires
			Microwave devices based on magnetic nanowires
			Magnetic nanowire metamaterials: Photonics and plasmonics
	Conclusions and future trends
	References
Part Three: Sensing, thermoelectric, robotics, biomedical and microwave applications
22
Template-assisted electrodeposited magnetic nanowires and their properties for applications
	Introduction
	Fe-Ga alloy nanowires used in tactile sensors
	Co/Cu multilayered nanowires for CPP-GMR structures
	Nanowires used for biomedical applications
	Long-range ordered porous AAO fabricated by double imprinting with line-patterned stamps
	Conclusions
	References
23
Nanowire transducers for biomedical applications
	Introduction
	Biocompatible magnetic nanowires
	Magnetic nanowires for drug delivery
	Magnetic nanowires for cancer treatment
	Magnetic nanowires as MRI contrast agents
	Magnetic nanowire cell scaffolds
	Conclusion
	Acknowledgments
	References
24
Thermopower measurements in magnetic nanowires
	Introduction
	Short history
	Thermopower
		Thermopower sources in series
		Thermopower sources in parallel
		Measurements in the membrane
		Measurements on the substrate
	Temperature-dependent thermopower
		Phonon-drag thermopower
		Influence of nanostructuring
	Origin of the magnetic field dependence
		Magneto-thermopower
	Conclusions
	References
25
Magnetostrictive Fe-Ga Nanowires for actuation and sensing applications
	Introduction to magnetostrictive Fe-Ga alloys
	Modeling and micromagnetics simulations of Fe-Ga nanowires
	Fabrication of Fe-Ga nanowires
	Structural and magnetic characterization of Fe-Ga and Fe-Ga/Cu nanowires
	Actuation using Fe-Ga/Cu nanowires
	Sensing using Fe-Ga/Cu nanowires
	Closing remarks
	References
26
Magnetically and chemically propelled nanowire-based swimmers
	Introduction
	Fabrication techniques for nanowire-based swimmers
	Magnetically driven nanowire-based swimmers
		Corkscrew locomotion
		Surface-walking locomotion
		Undulatory (S-like) locomotion
	Chemically propelled nanowire-based swimmers
	References
27
3D magnetic nanowire networks
	Introduction
	Template-assisted electrodeposition of 3D magnetic NW and NT networks
	Interplay between the magnetic and magneto-transport properties
		Magnetic and magneto-transport properties of interconnected homogenenous NW networks
		Interconnected Ni NT networks with controlled structural and magnetic properties
	NW network-based spin caloritronics
		Spin-dependent thermoelectric transport in multilayered NW networks
		Magnetic control in heat management
	Conclusion and future perspectives
	Acknowledgments
	References
28
Sensoric application of glass-coated magnetic microwires
	Introduction
	Glass-coated microwires
		Production
		Sensoric application of magnetic wires
			Magnetic field sensing
			Stress sensing using bistable microwires
			Stress in 3-D printed materials
			Sensing stress in biomedicine
			Sensing intracranial temperature
			Monitoring intracranial temperature in titanium implants
			Biocompatibility and technical compatibility of glass-coated microwires
			Chemical sensors based on bistable microwires
		Glass-coated Heusler-based SMART actuators
			Magnetocaloric applications
			Shape memory actuators: SMART actuators
	Conclusions
	Acknowledgments
	References
29
Orthogonal fluxgates based on magnetic microwires
	Introduction
	Working principle
		Second harmonic mode
		Fundamental mode
	Circumferential excitation field
	Bimetallic wires
	Noise and thermal treatment of the wire
	Offset
	Effect of wire geometry
	Applications
	References
	Further reading
30
Magnetic properties of amorphous microwires at microwaves and applications
	Introduction
	Tunable magnetic configuration in amorphous wire
		Tuning the anisotropy with applied stress and current annealing
		Temperature effects
	Dynamic permeability in microwires
		Permeability spectra in wires with near-circumferential anisotropy
		Permeability spectra in wires with the axial anisotropy near Tc
	High-frequency impedance: Effects of external dc field, stress, and temperature
		Magnetoimpedance plots vs. magnetic field
		Magnetoimpedance vs. external stress
		Impedance behavior near the Curie temperature
	Magnetopolarization effect and application to wireless sensors operating at GHz frequencies
		Electric polarization of a ferromagnetic wire
		Tuning the current distribution and polarization
		Application to wireless sensors
	Microwire composites as artificial dielectrics with tunable permittivity and permeability
		Effective permeability of wire composites
		Effective permittivity of composites with finite-length wires (wire dipoles)
		Effective permittivity of composites with continuous wires
	References
31
Nano-carbon/magnetic microwire hybrid fibers for tunable microwave functionalities
	Introduction
	Microwave absorption theory
	Microwave absorption properties of nano-carbon composites and hybrids
		CNT-based polymer composites
		Magnetically filled or decorated CNT
		Graphene-based polymer composites
		Graphene-based magnetic composites and hybrids
	Microwave absorption and metamaterial properties of amorphous wire composites
	Tunable microwave absorption of polymer composites incorporating nano-carbon/amorphous wire hybrid fibers
		Microwave absorption of polymer composites incorporating CNT/amorphous wire hybrid fibers
		Microwave absorption of polymer composites incorporating rGO/amorphous wire hybrid fibers
	Tunable negative permittivity of metacomposites incorporating nano-carbon/amorphous wire hybrid fibers
		Tunable negative permittivity of metacomposites incorporating CNT/amorphous wire hybrid fibers
		Tunable negative permittivity of metacomposites incorporating rGO/AW hybrid fibers
	Summary and future directions
		Summary
		Future directions
	Acknowledgments
	References
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