Nonequilibrium magnons : theory, experiment, and applications / Vladimir L. Safonov.

Format:

Book

Author/Creator:

Safonov, Vladimir, 1955-

Contributor:

Class of 1924 Book Fund.

Language:

English

Subjects (All):

Magnons.

Physical Description:

xiii, 190 pages : illustrations (black and white) ; 25 cm

Place of Publication:

Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, [2013]

Summary:

Starting with a brief review of developments in the magnon concept, and including original experimental results, the author presents methods of magnon excitation, and several basic models to describe magnon gas. He includes experiments on Bose-Einstein condensation of quasi-equilibrium magnons, as well as various applications of a magnon approach.

This book is written for the readers who have an interest in magnetic dynamics problems both for fundamental and applied research, and for the development of magnetic devices. It is also written in more or less academic style, and therefore can be used by graduate students and professors of technical universities. They can find here topics that may serve as the basis of future doctoral dissertations. For those who do not work directly with the magnetic systems, this book can give a bunch of ideas and analogies that can be useful in their research.

From the contents:

Harmonic Oscillator and Universal Language of Science

Magnons in Ferro-and Antiferromagnet

Relaxation of Magnons

Microwave Pumping of Magnons

Thermodynamic Description of Strongly Excited Magnon System

Bose-Einstein Condensation of Quasiequilibrium Magnons

Magnons in an Ultra-Thin Film

Collective Magnetic Dynamics in Nanoparticles Book jacket.

Contents:

1 Harmonic Oscillators and the Universal Language of Science 1

1.1 Harmonic Oscillator 1

1.1.1 Complex Canonical Variables 3

1.2 Classical Rotation 4

1.2.1 Classical Spin and Magnetic Resonance 5

1.3 Collective Variables and Harmonic Oscillators in k-space 8

1.3.1 Chain of Masses and Springs 8

1.3.2 Chain of Magnetic Particles 9

1.4 Discussion 11

2 Magnons in Ferromagnets and Antiferromagnets 13

2.1 Phenomenological Description 14

2.1.1 Magnons in a Ferromagnet 14

2.1.1.1 Holstein-Primakoff Transformation 16

2.1.1.2 The Spectrum of Magnons 19

2.2 Microscopic Modeling 21

2.2.1 Magnons in a Two-Sublattice Antiferromagnet 21

2.2.1.1 Hamiltonian 21

2.2.1.2 Spectrum of Magnons 25

2.2.2 Magnon-Magnon Interactions 26

2.3 Nuclear Magnons 28

2.4 Magnetoelastic Waves, Quasi Phonons 30

2.5 Discussion 33

3 Relaxation of Magnons 35

3.1 Master Equation 35

3.2 Relaxation of Bose Quasi Particles 37

3.2.1 Relaxation Process of Harmonic Oscillators 37

3.2.2 Magnon-Electron Scattering 39

3.3 Relaxation via an Intermediate Damped Dynamic System 43

3.4 Ferromagnetic Resonance Linewidth 46

3.5 Magnons and Macroscopic Dynamic Equation 49

3.5.1 Linearized Landau-Lifshitz Equation 50

3.6 Relaxation of Coupled Oscillations 51

3.6.1 Example 1: Nuclear Magnons 53

3.6.2 Example 2: Magnetoelastic Oscillations 54

3.7 Discussion 57

4 Microwave Pumping of Magnons 59

4.1 Linear Theory 60

4.1.1 Ferromagnetic Resonance 61

4.1.2 Threshold of Parametric Resonance 61

4.2 Parametric Resonance in a Resonator Cavity 63

4.3 Nonlinear SR Theory 67

4.4 Experimental Techniques 71

4.5 Experimental Results 73

4.5.1 Equivalent Circuit 74

4.5.2 SR Theory and Experiment 76

4.5.2.1 Modulation Response 79

4.6 Discussion 83

5 Thermodynamic Description of Strongly Excited Magnon System 85

5.1 Principal Equations 86

5.1.1 Hamiltonian 86

5.1.2 Unitary Transformation 87

5.1.3 Bogoliubov Transformation 88

5.1.4 Effective Temperature T_eff = 0 90

5.1.5 Effective Temperature T_eff ≠ 0 91

5.1.5.1 Maximum of Entropy 93

5.2 Exact Solutions 94

5.2.1 The Effective Temperature 96

5.2.1.1 Instantaneous Switching 96

5.2.1.2 Adiabatic Switching 97

5.2.1.3 Thermodynamic Stability 97

5.2.2 Collective Oscillations 98

5.3 Magnon Pumping in a Resonator 100

5.4 Discussion 101

6 Bose-Einstein Condensation of Quasi Equilibrium Magnons 103

6.1 Bose Gas of Magnons 103

6.1.1 Ideal Bose Gas 103

6.1.2 Mathematical Analogy with BEC 105

6.2 Quasi Equilibrium Magnons 105

6.2.1 Ideal Gas of Quasi Equilibrium Magnons 107

6.2.2 Example: Isotropic Spectrum 107

6.2.3 Kinetic Equations 109

6.2.3.1 The Case of T_eff = T 111

6.2.4 Magnon System with Bose Condensate 113

6.2.5 Magnetodipole Emission of Condensate 114

6.3 Fröhlich Coherence 115

6.4 Discussion 118

7 Magnons in an Ultrathin Film 119

7.1 Model 120

7.1.1 Magnetic Energy 121

7.2 Magnons 122

7.2.1 Magnon Interactions 124

7.2.2 Effective Four-Magnon Interactions 125

7.3 Example 126

7.4 Discussion 129

8 Collective Magnetic Dynamics in Nanoparticles 131

8.1 Long-Lived States in a Cluster of Coupled Nuclear Spins 134

8.2 Electronic Spins 136

8.3 Spin-Echo Logic Operations 138.

Notes:

Includes bibliographical references and index.

Local Notes:

Acquired for the Penn Libraries with assistance from the Class of 1924 Book Fund.

ISBN:

3527411178

9783527411177

OCLC:

821681555

Publisher Number:

99953368764