Physics of Magnetism Magnetic Materials 2011 Part 2 doc

... CONTENTS vii Chapter 14 . Soft -Magnetic Materials 14 7 14 .1. Introduction 14 7 14 .2. Survey of Materials 14 8 14 .3. The Random-Anisotropy Model 15 6 14 .4. Dependence of Soft -Magnetic Properties ... 13 . High-Density Recording Materials 13 1 13 .1. Introduction 13 1 13 .2. Magneto-Optical Recording Materials 13 3 13 .3. Materials for High-Density Magnetic Recording 13 9 References 14 5 ... 15 8 14 .5. Head Materials and Their Applications 15 9 14 .5 .1 High-Density Magnetic- Induction Heads 15 9 14 .5.2 Magnetoresistive Heads 16 1 References 16 3 Chapter 15 . Invar Alloys 16 5...

... discussed 23 SECTION 4 .2. FERROMAGNETISM all the steps from Eq. (3.1.4) to Eq. (3 .2. 2). This means that Eq. (3 .2. 2) should actually be written in the form Introducing the magnetic susceptibility ... the J = 5 /2 and J = 7 /2 levels but also due to a difference in energy separation between the levels of the J = 5 /2 manifold (g = 2/ 7 and the levels of the J = 7 /2 manifold (g = 52/ 63). Generally ... can be obtained by means of 14 CHAPTER 3. PARAMAGNETISM OF FREE IONS in Chapter 8). For one has J = 9 /2 and g = 8/11 (see Table 2. 2.1). Furthermore, we make use of the following values and...

... then given by 32 CHAPTER 4. THE MAGNETICALLY ORDERED STATE field dependence of the magnetization behaves as shown by curve (a) in Fig. 4 .3. 3. The slope of the first part of this curve is ... discuss the magnetic coupling in these materials in somewhat more detail. We consider a ferrimagnetic compound consisting of two types of magnetic atoms A and B, occupying the sites of two different ... represent the three types of cooperative magnetism leading to ordered magnetic moments as follows: Ferromagnetism Antiferromagnetism and Ferrimagnetism and 40 CHAPTER 4. THE MAGNETICALLY ORDERED...

... presence of fourfold-symmetry axes, only terms with n = 4 and m = 0, ± 4 are retained, which leads to where the coefficients of the terms have been calculated with the help of Eq. (5.2 .4) , keeping ... magnetic field will lift the degeneracy of each of the three doublet levels. Since a given magnetic field lowers and raises the energy of each of the sets of doublet levels in a different way, ... electron shells of ions. These currents are equivalent to an induced moment present on each of the atoms. The diamagnetism is a consequence of Lenz’s law stating that if the magnetic flux enclosed...

... magnetic field of is the magnetic field in an infinitely long solenoid consisting of n turns per meter of coil and carrying an electric current of The unit of the magnetic induction or magnetic ... lines are diluted in diamagnetic materials, concentrated in paramagnetic materials, and strongly concentrated in ferromagnetic materials. In diamagnetic and paramagnetic materials, small applied ... external magnetic induction, different types of magnetic behavior can be observed, comprising diamagnetism, paramagnetism, or ferromagnetism. It will be clear that in diamagnetic materials, ...

... fixed temperature the entropy of a system of magnetic moments can be lowered by the application of a magnetic field. The entropy is a measure of the disorder of a system, the larger its disorder, ... intersection of the two magnetization curves mentioned. Illustrative examples of measurements of 97 94 CHAPTER 10. CALORIC EFFECTS IN MAGNETIC MATERIALS In the absence of the magnetic field, ... MAGNETOMETER where is the magnetic moment of a small sample located in an area where the field gradient has a constant value. For various types of magnetically ordered materials, in particular, it is...

... descriptions of magnetic anisotropy and its determination can be found in the textbooks of Chikazumi (1966) and McCaig and Clegg (19 87) . References Chikazumi, S. (1966) Physics of magnetism, ... reversal is the existence of magnetic- domain structures. Magnetic particles of sufficiently large size will generally not be uniformly magnetized but rather be composed of magnetic domains that ... after removal of the magnetizing field and hence is a measure of the strength of the magnet, whereas the coercivity Permanent -magnetic materials are characterized by a field dependence of the magnetization...

... temperature dependence of the Faraday rotation. This means that 14 Soft -Magnetic Materials 14.1. INTRODUCTION Soft -magnetic materials are mainly used in magnetic cores of transformers, motors, ... magneto-optical rotation 1 49 SECTION 14.2. SURVEY OF MATERIALS thousands of tons. The major part of this material is used for the generation and distribution of electrical energy of which the application ... discussing the most important magnetic- recording materials currently employed. More details can be found in the surveys of Hibst and Schwab ( 199 4) and Richter ( 199 3). Particulate recording media...

... polycrystalline alloys and offer the possibility of tailoring superior soft -magnetic properties for specific applications. In Fig. 14.2.8, the soft -magnetic properties of various groups of materials are ... dependence of the magnetic properties of various types of soft -magnetic materials is compared in Fig. 14.4.1. The random-anisotropy model apparently provides a good description of the magnetic ... two sections, both types of materials will be briefly discussed. Soft -magnetic materials are widely employed for the fabrication of magnetic recording heads. These materials must have a high...

... magnets, 119 propagation field for Bloch walls, 113 radius of 4f electron charge cloud, 46 random-anisotropy model, 156 rare-earth-based magnet materials, 119 soft ferrites, 153 soft -magnetic materials, ... slip-induced anisotropy, 152 117 , 118 118 pair ordering, 152 pair-ordering model, 134 paramagnetic Curie temperature, 23, 27 paramagnetism of free ions, 11 particulate media, 140, 143 ... 9 magnetic properties of the rare-earth elements, 8 magnetic quantum number, 3 magnetic recording, 139 magnetic- recording medium, 139 magnetic splitting of the ground-multiplet, 16 magnetic...