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Micromagnetism and the Microstructure of Ferromagnetic Solids : Cambridge Studies in Magnetism - Helmut Kronmuller

Micromagnetism and the Microstructure of Ferromagnetic Solids

Cambridge Studies in Magnetism

Hardcover Published: 26th March 2015
ISBN: 9780521331357
Number Of Pages: 450

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The main theme of this book is micromagnetism and microstructure as well as the analysis of the relations between characteristic properties of the hysteresis loop and microstructure. Also presented is an analysis of the role of microstructure in the fundamental magnetic properties (for example magnetorestriction or critical behaviour) of crystalline and amorphous alloys. The authors apply the theory of micromagnetism to all aspects of advanced magnetic materials including domain patterns and magnetization processes under the influence of defect structures. Coverage includes modern developments in computational micromagnetism and its application to spin structures of small particles and platelets. It will be of interest to researchers and graduate students in condensed matter, physics, electrical engineering and materials science, as well as to industrial researchers working in the electrotechnical and recording industry.

Acknowledgementsp. xi
Introductionp. 1
Referencesp. 8
Units of magnetic propertiesp. 9
Magnetic Gibbs free energyp. 11
Introductionary remarksp. 11
Magnetic energy termsp. 13
Exchange energyp. 14
Short-range exchange interactionsp. 14
Long-range exchange interactionsp. 17
Magnetocrystalline anisotropy energyp. 20
Magnetostatic energiesp. 25
Elastic potential of a ferromagnetp. 28
Strain tensor in ferromagnetic materialsp. 28
Determination of strain tensorsp. 28
Derivation of the magnetoelastic potentialp. 31
Summaryp. 35
Referencesp. 37
Basic micromagnetic equilibrium conditionsp. 40
Static micromagnetic equationsp. 40
Micromagnetic equations in polar coordinatesp. 44
Micromagnetic equations in terms of swirls and magnetic charesp. 44
Linearized micromagnetic equationsp. 45
Referencesp. 50
Domain walls in crystalline and amorphous solidsp. 51
General remarksp. 51
Bloch wallsp. 51
Effect of magnetostrictive deformationsp. 55
Effect of internal stressesp. 57
Bloch walls in cubic crystalsp. 57
Neel walls in bulk materials and thin filmsp. 64
General remarksp. 64
Neel walls in bulk crystalsp. 65
Neel walls in thin filmsp. 66
Phase diagrams of Neel and Bloch walls in thin filmsp. 69
Referencesp. 70
Interaction of domain walls with defectsp. 71
Introductionary remarksp. 71
Interaction energy of domain walls with point defectsp. 71
180[degree]-wall in amorphous alloys with uniaxial anisotropyp. 74
180[degree]-wall in [alpha]-Fep. 75
Interaction forces of domain walls with point defectsp. 75
Interaction of Bloch walls with dislocationsp. 75
Straight dislocation linesp. 77
Dislocations of length l parallel to the domain wall plane (x, y)p. 78
Dislocations intersecting the domain wallsp. 79
Straight dislocation dipolesp. 80
Dislocation loopsp. 81
Interaction of domain walls with planar defectsp. 81
Pinning by thin planar defectsp. 81
Pinning by extended planar defectsp. 85
Pinning by phase boundariesp. 86
Referencesp. 88
Coercivity of modern magnetic materialsp. 90
Introductionp. 90
Micromagnetism of hard magnetic materialsp. 95
Homogeneous rotationp. 96
Inhomogeneous rotation by the curling modep. 99
Inhomogeneous rotation by the buckling modep. 101
Critical diameters of single domain particlesp. 103
Thermal stability limitp. 103
Crossover diameter for nucleation processesp. 104
Critical diameter for domain formationp. 104
Comparison with experimentp. 107
Nucleation under oblique magnetic fieldsp. 108
Homogeneous rotationp. 108
Curling modep. 113
Nucleation in magnetically soft regionsp. 114
Nucleation in inhomogeneous misaligned grainsp. 117
Micromagnetic analysis of the coercive field of modern permanent magnetsp. 119
Nucleation versus pinningp. 119
Analysis of the temperature dependence of the coercive fieldp. 122
Nanocrystalline and composite nanocrystalline magnetsp. 126
Nanostructured, nanocrystalline Sm[subscript 2]Co[subscript 17]-based permanent magnetsp. 131
Alternative coercivity models - the nucleus expansion modelp. 141
Referencesp. 144
Statistical theory of domain wall pinningp. 148
Statistical pinning potentialp. 148
Applications of the statistical pinning theoryp. 151
Dislocations in crystalline metalsp. 151
Dislocation dipolesp. 153
Point defectsp. 155
Amorphous alloysp. 155
Intrinsic fluctuations of exchange and local anisotropy energyp. 156
Internal stress sourcesp. 158
Coercive field due to surface irregularitiesp. 161
Nanocrystalline alloysp. 164
Referencesp. 172
Law of approach to ferromagnetic saturation and high-field susceptibilityp. 174
Introductionp. 174
Approach to saturation in uniaxial crystalsp. 176
Approach to saturation in cubic crystalsp. 177
Approach to saturation in the presence of stress sourcesp. 177
Introductionp. 177
Isotropic spherical defectsp. 179
Dislocation loopsp. 183
Straight dislocation linesp. 184
Dislocation groupsp. 187
Dislocation dipolesp. 191
Anisotropy of the high-field susceptibilityp. 193
Amorphous alloysp. 196
General remarksp. 196
Magnetostatic fluctuationsp. 198
Magnetocrystalline fluctuationsp. 200
Magnetoelastic fluctuationsp. 201
Analysis of experimental resultsp. 207
Nonmagnetic holes and nonferromagnetic precipitationsp. 217
Referencesp. 224
Microstructure and domain patternsp. 225
Origin of domain patternsp. 225
Laminar domain patternsp. 227
Landau structurep. 227
Kittel structurep. 228
Partial Landau-Kittel structurep. 229
Kittel-type structure for in-plane easy directionp. 231
The [mu]* -correctionp. 232
Branching of domains in hard magnetic materialsp. 233
Domain patterns in amorphous alloysp. 237
As-quenched amorphous alloysp. 238
Magnetic annealing of amorphous alloysp. 243
Domain structure and magnetization processesp. 243
Stress-induced magnetic anisotropyp. 247
Stripe domains in thin ferromagnetic filmsp. 249
Dislocations and domain patternsp. 255
Introductionp. 255
Domain patterns in plastically deformed Ni-single crystalsp. 255
Domain patterns in plastically deformed Fe-single crystalsp. 261
Micromagnetic background of the magnetoelastic coupling energy due to dislocationsp. 263
Ripple structuresp. 269
Referencesp. 272
Magnetic after-effects in amorphous alloysp. 274
Introductionp. 274
Double-well model of magnetic after-effects in amorphous alloysp. 275
Stabilization energy of domain wallsp. 278
Formation of induced anisotropyp. 283
Basic experimental resultsp. 284
Concluding remarksp. 292
Referencesp. 293
Magnetostriction in amorphous and polycrystalline ferromagnetsp. 295
Outline of the problemsp. 295
Polycrystalline model of amorphous ferromagnetsp. 297
Basic computational ideasp. 299
Mathematical formalismp. 302
Balance-of-force methodp. 302
Incompatibility methodp. 306
Zeroth- and first-order termsp. 308
Results for the saturation magnetostriction of ferromagnetsp. 310
Field dependence of magnetostrictionp. 313
Referencesp. 316
Appendixp. 317
Micromagnetic theory of phase transitions in spatially disordered spin systemsp. 320
Classification of disordered spin systemsp. 321
Phase transition in random exchange ferromagnetsp. 323
Critical behaviourp. 323
Crossover regime to mean field behaviourp. 325
Molecular field theory and Landau-Ginzburg theoryp. 327
Extended Landau-Ginzburg theoryp. 332
Correlated molecular field theoryp. 334
Physical motivationp. 334
Calculation of the paramagnetic zero-field susceptibilityp. 339
Random ferrimagnets, spin glasses and random anisotropy magnetsp. 347
Dynamic correlated molecular field theoryp. 350
Referencesp. 353
Computational micromagnetism of thin platelets and small particlesp. 356
Introductionp. 356
Applications of the finite difference methodp. 357
Applications of the finite element methodp. 364
Discretization and adaptive mesh refinementp. 364
Discretization of the Gibbs free energy used for computational micromagnetismp. 366
Magnetic structures and magnetization processes in thin plateletsp. 371
Magnetic structures and magnetization processes in small particlesp. 380
Soft magnetic particles in a hard magnetic matrixp. 384
Assemblies of nanocrystalline grainsp. 385
Referencesp. 399
Computational micromagnetism of dynamic magnetization processesp. 402
Landau-Lifshitz and Gilbert equationsp. 402
Characteristic time rangesp. 405
Magnetization reversal in thin filmsp. 408
Discretization of the Landau-Lifshitz-Gilbert equationp. 409
Dynamic nucleation fieldp. 410
Dynamics of thermally activated reversal processesp. 416
Thermal fluctuationsp. 416
Thermally activated relaxationp. 420
Referencesp. 422
Scaling laws of the statistical pinning theoryp. 423
Indexp. 428
Table of Contents provided by Ingram. All Rights Reserved.

ISBN: 9780521331357
ISBN-10: 0521331358
Series: Cambridge Studies in Magnetism
Audience: Professional
Format: Hardcover
Language: English
Number Of Pages: 450
Published: 26th March 2015
Publisher: Cambridge University Press
Country of Publication: GB
Dimensions (cm): 24.4 x 17.0  x 2.5
Weight (kg): 1.02