Magnetic Measurement Techniques for Materials Characterization

Description

This book discusses the most commonly used techniques for characterizing magnetic material properties and their applications. It provides a comprehensive and easily digestible collection and review of magnetic measurement techniques. It also examines the underlying operating principles and techniques of magnetic measurements, and presents current examples where such measurements and properties are relevant. Given the pervasive nature of magnetic materials in everyday life, this book is a vital resource for both professionals and students wishing to deepen their understanding of the subject. Preface Contents About the Editors Part I Units in Magnetism Units for Magnetic Quantities 1 The Centimeter-Gram-Second System of Units 2 The Rationalized Meter-Kilogram-Second-Ampere System 3 The International System of Units 4 Conversion Factors 5 Epilogue References Part II Inductive and Force-Based Techniques for Measuring Bulk Magnetic Properties Vibrating Sample Magnetometry 1 Magnetic Measurement Techniques 2 Electromagnet-Based VSM 3 VSM Components and Extensions Theory: Anisotropy Constants from Vector Magnetization Data 4 First-Order Reversal Curves (FORC) 5 Summary References Recent Advances in SQUID Magnetometry 1 Introduction to SQUID Magnetometry 2 Primary Components of a SQUID-Based Magnetometer Sample Transport Second-Order Gradiometer The DC SQUID Properties of SC Loops Josephson Junctions SQUID Functionality Flux Locking 3 Detection Modes Traditional DC Scan Squid-VSM Strengths and Weaknesses of each Detection Mode 4 Sample Environment Temperature Control and Thermometry Magnetic Field Control 5 Improving Measurement Accuracy Sample Mounting Considerations: Basics Background Subtraction Background Subtraction: Traditional DC Scan Background Subtraction: SQUID-VSM Sample Centering and Size/Shape Effects Superconducting Solenoids-Remanent Field 6 Additional Capabilities of the SQUID Magnetometer 7 Conclusions References AC Susceptometry 1 Introduction Theory of AC Susceptibility Units and Conventions Demagnetizing Factors Magnetic Relaxation Screening AC Susceptometer Design Working with an AC Susceptometer Research Examples Differential Probe of Magnetism Determining the Skin Depth in Conducting Samples Measuring Spin Relaxation in Magnetic Materials Summary References DC Hysteresigraphs for Hard and Soft Materials 1 Introduction to DC Hysteresigraphs for Hard Magnetic Materials 2 Why Do we Need a DC Hysteresigraph for Hard Magnetic Materials? 3 Materials to Test 4 Theory 5 Measurement Equipment/Block Diagram 6 Making a Measurement Sample Magnetization Initial Curves 7 Alternative Measurement Sensors 8 Temperature Measurements 9 Limitations of this Technique Not Useful for Thin Films Quality of the Closed Circuit Assumes Homogeneous Materials H Field Accuracy Low-Coercivity Materials 10 Introduction to DC Hysteresigraphs for Soft Magnetic Materials 11 Why Do we Need a DC Hysteresigraph for Soft Magnetic Materials? 12 Theory and Test Circuit 13 Making a Measurement Magnetizing Field Control Initial Curve 14 Alternative Testing Circuits for Bulk Soft Magnetic Materials 15 Temperature Measurements 16 Limitations of this Technique Specimen Shape Need to Wind the Ring Integrator Drift 17 Summary References Radio-Frequency Transverse Susceptibility as a Probe to Study Magnetic Systems 1 Introduction 2 Theoretical Background 3 Measurement Technique 4 Choice of Circuit Components 5 Magnetic Systems Investigated Using Transverse Susceptibility Dipolar Interactions within Soft Ferrite Particles Magnetic Anisotropy in Exchange-Biased Nanostructures Magnetic Anisotropy in Ferromagnetic Epitaxial Thin Films Magnetocrystalline Anisotropy-Driven Phase Transition in Strongly Correlated Electron Systems 6 The Future of Transverse Susceptibility References Alternating Gradient Magnetometry 1 Introduction 2 Sensitivity 3 AGM Limitations 4 Summary References Nanomechanical Torque Magnetometry 1 Introduction 2 Torque Sensing and Magnetometry Basics 3 Experimental Apparatus, Sensor Design, and Fabrication Optical Detection Schemes Apparatus Torque Sensor Design Torque Sensor Fabrication 4 Magnetic Properties and Parameters Magnetic Hysteresis Mechanical Torque Detection of Spin Resonance Multi-Axis Torque Magnetometry Einstein-de Haas Torques 5 Micromagnetic Simulation 6 Calibration and Sensitivity 7 Nanomechanical Torque Magnetometry in Comparison to Other Methods: Summary References Part III Imaging Techniques Magneto-Optical Microscopy 1 Introduction 2 Magneto-Optical Effects Electromagnetic Basics Kerr and Faraday Effect Faraday Effect Kerr Effect Voigt Effect Gradient Effect 3 Physical Aspects of Magneto-Optical Microscopy Domain Contrast Depth Sensitivity Resolution 4 Technical Aspects of Magneto-Optical Microscopy Microscopy High-Resolution Microscopy Overview Microscopy Camera Systems Time-Resolved Kerr Microscopy Temperature-Dependent Microscopy Indicator Films MOKE Magnetometry 5 Advanced Methodology Separation of Effects Quantitative Kerr Microscopy Quantitative Imaging of Magnetisation Dynamics Voigt and Gradient Effect Microscopy Depth-Selective Imaging 6 Summary and Outlook References X-Ray Magnetic Circular Dichroism and X-Ray Microscopy 1 Introduction 2 X-Ray Absorption Spectroscopy Elemental and Chemical Contrast Magnetic Contrast Sum Rule Analysis 3 X-Ray Microscopy Photoemission Electron Microscopy Transmission X-Ray Microscopy Scanning X-Ray Microscopy Ptychography 4 Summary References Transmission, Scanning Transmission, and Scanning Electron Microscopy 1 Introduction Overview Electron-Solid Interaction Elastic Scattering Inelastic Scattering Secondary and Auger Electron Emission Diffraction and Imaging through Multiple Electron Lenses 2 Transmission Electron Microscopy and Scanning Transmission Electron Microscopy Instrumentation Specimen Structural Analysis Electron Diffraction TEM Imaging Bright-Field/HAADF STEM Imaging Compositional Mapping Using EDX/EELS Magnetic (Scanning) Transmission Electron Microscopy Basics Lorentz Microscopy Differential Phase Contrast Lorentz Imaging Electron Holography 3 Scanning Electron Microscopy Instrumentation Structural Analysis Secondary Electron (SE) and Backscattered Electron (BSE) Imaging Electron Backscattering Diffraction (EBSD) WDX Imaging (EPMA) Magnetic Microscopy Type-I and Type-II Contrast Scanning Electron Microscopy with Polarization Analysis (SEMPA) 4 Summary References Part IV Field Sensing and Neutron Scattering in Magnetism Magnetic Field Sensing Techniques 1 Magnetic Field Sensors: Overview 2 Hall Sensors Hall Sensors: Principles Hall Sensors: Benefits and Limitations Hall Sensors: Applications and Specifications Hall Sensors: Recent Developments 3 Fluxmeters Fluxmeters: Principles Fluxmeters: Benefits and Limitations Fluxmeters: Applications and Specifications Fluxmeters: Recent Developments 4 Fluxgate Magnetometers Fluxgates: Principles Fluxgates: Benefits and Limitations Fluxgates: Applications and Specifications Fluxgates: Recent Developments 5 Magnetoresistive Sensors AMR Sensors: Principles GMR Sensors: Principles Magnetoresistive Sensors: Benefits and Limitations Magnetoresistive Sensors: Applications and Specifications Magnetoresistive Sensors: Recent Developments 6 NMR Magnetometers NMR Magnetometers: Principles NMR Magnetometers: Benefits and Limitations NMR Magnetometers: Applications and Specifications NMR Magnetometers: Recent Developments 7 Calibration Calibration: Magnetic Field Units Calibration: NMR as a Secondary Standard Calibration: Low-Field Sensors Calibration: Three-Axis Sensors 8 Magnetic Field Sensors: Conclusion References Introduction to Neutron Scattering as a Tool for Characterizing Magnetic Materials 1 Introduction 2 Neutron Sources 3 Physics of Neutron Scattering 4 Neutron Diffraction 5 Neutron Reflectivity 6 Small Angle Neutron Scattering 7 Polarization Analysis 8 Time Resolution 9 Summary References Neutron Scattering in Magnetism: Fundamentals and Examples 1 Introduction 2 Fundamentals of Neutron Scattering Properties of Neutrons The Scattering Problem Neutron Interactions at Low Energy Nuclear Scattering Elastic Nuclear Scattering Inelastic Nuclear Scattering Magnetic Scattering Physical Meaning of the Operator Matrix Elements of Dipole Approximation Magnetic Scattering Cross Section in the Dipole Approximation 3 Neutron Scattering by a Crystal Nuclear Scattering Scattering by Phonons Magnetic Scattering Magnetic Inelastic Scattering Scattering by Spin-Waves 4 Polarization Analysis 5 Magnetic Crystallography Describing Magnetic Structures 6 Neutron Powder Diffraction Some Ideas About the Rietveld Method Selected Examples Magnetic Structure of MnO Antiferromagnetic Structures with =0 in A2FeX5·H2O (A=K, Rb, X=Cl, Br) The Problem of the Global Phase in Ca3Co2-xFexO6 Incommensurate Spiral Magnetic Structure in LiFeAs2O7 Long Period Helical Structures 7 Single Crystal Neutron Diffraction Modulated Magnetic Structures in Multiferroics Spin-Flop Transition and Magnetic Structures in the Hybrid Multiferroic (NH4)2FeCl5·H2O Magnetic Ordering by Dipolar Interactions in Single-Molecule Magnet Mn12-Acetate Trapping the Different Magnetic Phases in the Chiral Molecular Magnet [Cr(CN)6][Mn(S)-pnH(H2O)]·(H2O) 8 Polarized Neutron Diffraction Spin Density Experiments in p-O2N-C6F4CNSSN and A2FeX5·H2O (A=K, Rb, X=Cl, Br) Determination of Atomic Site Susceptibility Tensors 9 Spherical Neutron Polarimetry Proving the Magneto-Electric Coupling in the Molecular Multiferroic (NH4)2FeCl5·H2O Elucidating the Magnetic Order in GdB4 10 Small-Angle Neutron Scattering in Magnetism Stroboscopic SANS Experiments on Skyrmionic Lattices (SKL) 11 Magnetic Inelastic Scattering Understanding Magnetic Interactions in K2FeCl5·D2O Neutron Spectroscopy in Magnetic Molecular Clusters 12 Other Neutron Scattering Techniques Quasielastic Neutron Scattering Neutron Spin Echo Techniques Neutron Reflectivity 13 Conclusions References Part V High Frequency Magnetization Dynamics Radio-Frequency (RF) Permeameter 1 Introduction 2 Overview of RF Permeameters RF Permeameters Based on Transmission and Reflection of Propagating Electromagnetic Waves RF Permeameters Based on Inductive Response 3 Transformer Coupled Permeameter System Overview of TC-Perm Calibration Algorithm of TC-Perm Sensitivity Demonstration of TC-Perm 4 Summary References Ferromagnetic Resonance 1 Introduction 2 Ferromagnetic Resonance Condition Kittel Equation Smit-Beljers Equation Ferromagnetic Resonance Lineshape 3 Experimental Methods Resonant Microwave Cavity-Based FMR Shorted Waveguide FMR Other Transmission Line-Based FMR Vector Network Analyzer FMR Electrically Detected FMR 4 Examples Saturation Magnetization and Perpendicular Anisotropy In-plane Anisotropies Conductivity-Like Damping in Epitaxial Iron Films 5 Summary References Part VI Applications to Current Magnetic Materials Magnetic Characterization of Geologic Materials with First-Order Reversal Curves 1 Introduction 2 The Preisach Model of Hysteresis The Classical Preisach Model Modifications of the Classical Preisach Model Preisach Models of Selected Measurement Protocols Low-Field Susceptibility IRM Acquisition Curves DC Demagnetization Curves AF Demagnetization of IRM ARM Acquisition and Demagnetization Coercivity Distributions 3 The FORC Protocol Definitions Selected Properties of the FORC Function FORC Measurements The FORC Protocol Choosing the FORC Protocol Parameters Field Control, Measurement Sensitivity, and Resolution Drift and Stacking FORC Processing Preprocessing Theoretical Principles of FORC Function Estimation Improved Regression Methods Overfitting, Underfitting, and Error Estimates Variable Smoothing Protocols The Central Ridge The Vertical Ridge Processing FORC Data Associated with Thin Hysteresis Loops Smoothing Factor Limitations Along the Measurement Coordinates Processing FORC Data Associated with Highly Squared Hysteresis Loops Demagnetizing Fields and FORC Deshearing FORC Data Rendering 4 FORC Diagrams of Natural Particle Assemblages Single-Domain Particles Uniaxial SD Particles: Stoner-Wohlfarth Model Thermally Activated SD Particles Viscous SD Particles and the Vertical Ridge Weak Magnetostatic Interactions Between SD Particles Mean-Field Interactions SD Particles with Multiaxial Anisotropy Selected Natural Examples The Pseudo-Single-Domain Magnetic Behavior Two-State Magnetic Systems Rock and Paleomagnetic Significance of Two-State Systems Multistate Systems: The PSD FORC Signature Multidomain Particles 5 Conclusions and Outlook References Characterization of Magnetic Nanostructures with the First-Order Reversal Curves (FORC) Diagram Technique 1 Introduction 2 Classical Preisach Model 3 Magnetic Ensembles of Real Magnetic Hysterons 4 Results of Simulations 5 Summary References FORC Diagrams in Magnetic Thin Films 1 The FORC Measurement Sequence 2 FORC Measurements of Isolated Granular Films 3 FORC Measurements of Interacting Granular Films 4 FORC Measurements of Continuous Films with In-Plane Anisotropy 5 FORC Measurements of Continuous Films with Out-of-Plane Anisotropy 6 FORC Measurements of Heterostructured Films Exchange Springs 7 Dynamic FORC Measurements 8 FORC Measurements Beyond Magnetometry Magnetoresistance Metal-Insulator Transitions 9 Final Thoughts References First-Order Reversal Curve (FORC) Measurements for Decoding Mixtures of Magnetic Nanowires 1 Introduction 2 Quantitative Decoding 3 Measurement Speed 4 Data Processing 5 Summary and Future Outlooks References Soft Magnetic Materials 1 Introduction 2 Soft Magnetic Materials Classes 3 Measurement Techniques for Materials Characterization in Emerging SMMs 4 Conclusion References Permanent Magnet Materials 1 Introduction 2 General Notes for Magnetization Curve Measurements of Permanent Magnets 3 Coercivity Analysis of Permanent Magnets Static Analysis Thermal Activation Analysis 4 Magnetization Reversal Process of Permanent Magnets Magnetic Imaging FORC Analysis 5 Summary References Magnetocaloric Characterization of Materials 1 Introduction 2 Types of Magnetocaloric Materials 3 Relevant Magnitudes for the Characterization of Magnetocaloric Materials Isothermal Entropy Change Adiabatic Temperature Change Refrigerant Capacity and Its Variants 4 Indirect Characterization Methods Magnetometry Demagnetizing Field Calorimetry 5 Direct Characterization Methods 6 Magnetocaloric Effect to Study Phase Transitions Critical Scaling in Second-Order Phase Transition Materials Quantitative Determination of the Order of the Phase Transition Study of Thermomagnetic Hysteresis in Magnetocaloric Materials by Using TFORC 7 Conclusions References Magnetostrictive Materials 1 Introduction Basic Concepts and Definitions Magnetostriction Magnetoelastic Effects ∆E Effect Magnetoelastic Waves and Resonance Magnetostrictive Materials 2 Magnetostriction Measurement Techniques Direct Measurements Strain Gauges Capacitive Bridges Tunneling and Atomic Force Tip Measurements Optical and Interferometric Methods Indirect Measurements Dependence of Permeability on Stress Small Angle Magnetization Rotation Ferromagnetic Resonance Methods Thin Film Methods 3 Applications Magnetostrictive Actuators Magnetoelastic Sensors Energy Harvesting 4 Summary References Magnetic Properties of Granular L10 FePt Films for Heat-Assisted Magnetic Recording (HAMR) Applications 1 Grain Interactions 2 Thermal Stability 3 HK and TC Distributions 4 Summary References Biological and Medical Applications of Magnetic Nanoparticles 1 Introduction 2 Requirements of Magnetic Nanoparticles for Bio-Applications 3 Synthesis Methods 4 Characterization Methods Sample Preparation Morphology, Size, and Structural Characterization Surface Properties Concentration Magnetic Characterization Preclinical Characterization 5 Magnetic Bio-Separation 6 Magnetic Nanoparticles for Biosensing Spintronic Sensors SQUID and Atomic Magnetometers Applied to Biosensing Faraday Induction Coil Biosensors Magnetic Lateral Flow Immunoassays Magnetic Nanoparticles in Nonmagnetic Detection 7 Magnetic Nanoparticles for Bio-Imaging 8 Magnetic Hyperthermia, Magneto-mechanical Disruption, Drug Delivery, and Tissue Regeneration 9 Conclusion and Prospects References Index