Solid - State Magnetism

ISBN-13: 9781461367482 / Angielski / Miękka / 2012 / 206 str.

Crangle, John

Opis

Solid state magnetism is important and attempts to understand magnetic properties have led to an increasingly deep insight into the fundamental make up of solids. Both experimental and theoretical research into magnetism continue to be very active, yet there is still much ground to cover before there can be a full understanding. There is a strong interplay between the developments of materials science and of magnetism. Hundreds of new materials have been dis- covered, often with previously unobserved and puzzling magnetic prop- erties. A large and growing technology exists that is based on the magnetic properties of materials. Very many devices used in everyday life involve magnetism and new applications are being invented all the time. Under- standing the fundamental background to the applications is vital to using and developing them. The aim of this book is to provide a simple, up-to-date introduction to the study of solid state magnetism, both intrinsic and technical. It is designed to meet the needs and interests of advanced undergraduate students reading physics; of postgraduates in physical and materials sciences and in engineering; and also those of the practising scientist specializing in another area who requires an introduction to magnetism.

Spis treści

1 Introduction.- 1.1 Basic magnetic properties.- 1.1.1 Ferromagnetic materials.- 1.1.2 Paramagnetism.- 1.1.3 Diamagnetism.- 1.1.4 Antiferromagnetism.- 1.1.5 Ferrimagnetism.- 1.1.6 Helimagnetism.- 1.2 Units in magnetism.- 2 Localized magnetism associated with the ion cores.- 2.1 The origins of the magnetic properties of materials.- 2.2 The magnetic moment of a single free ion.- 2.2.1 Hund’s rules.- 2.2.2 Combination of L and S to form J.- 2.2.3 Units of magnetic moment.- 2.3 The magnetic moment of an assembly of atoms, without interactions.- 2.4 Paramagnetic susceptibility of an array of atoms.- 2.5 Comparison with experiment.- 2.5.1 Experimental behaviour of rare earth salts and metals.- 2.5.2 Experimental behaviour of transition series salts.- 2.5.3 Crystal field effects.- 2.5.4 Direct measurement of the g-factor.- 2.6 Ferromagnetism in the local moment model, with interactions.- 2.6.1 Calculation of the spontaneous magnetization.- 2.6.2 Relationship between the molecular field coefficient and the Curie Temperature.- 2.6.3 Susceptibility above the Curie temperature.- 2.6.4 Comparison with experiment.- 3 Magnetism associated with band electrons.- 3.1 Collective electron theory: general solution.- 3.2 Paramagnetism without interactions.- 3.2.1 Comparison with experiment.- 3.3 Paramagnetism with interactions.- 3.3.1 Comparison with experiment.- 3.4 Ferromagnetism in the band model.- 3.4.1 Paramagnetism above the Curie temperature.- 3.5 Magnetic moments of pure metals and alloys.- 3.5.1 The rigid band model.- 3.5.2 Nickel.- 3.5.3 Cobalt.- 3.5.4 Iron.- 3.5.5 Face-centred cubic nickel-copper and cobalt-copper alloys.- 3.5.6 Other alloys of nickel and cobalt.- 3.5.7 Face-centred cubic binary alloys between transition elements.- 4 Techniques of making magnetic measurements.- 4.1 Measurement of magnetization.- 4.1.1 The induction method.- 4.1.2 Vibrating sample magnetometer.- 4.1.3 The force method.- 4.2 Measurement of paramagnetic susceptibility.- 4.2.1 The Gouy method.- 4.2.2 Effect of ferromagnetic impurities on susceptibility measurements.- 4.3 Dipole moment methods — SQUIDS.- 4.3.1 SQUID magnetometry.- 4.3.2 The phase of a pair wave.- 4.3.3 Effect of a magnetic field.- 4.3.4 Circular conductor.- 4.3.5 Quantum interference.- 4.3.6 Quantum interferometer.- 4.4 Derivation of spontaneous magnetization from experimental data.- 4.4.1 Measurement of Curie temperature.- 4.5 The generation of magnetic fields.- 4.5.1 Solenoid magnets with air cores.- 4.5.2 Power consumption and dissipation in a solenoid.- 4.5.3 Mechanical effects in solenoids.- 4.5.4 Superconducting solenoids.- 4.5.5 Iron-cored electromagnets.- 4.5.6 Pulsed magnetic fields.- 4.6 The measurement of magnetic field.- 4.6.1 Measurement of magnetic flux.- 4.6.2 Ballistic galvanometer.- 4.6.3 Fluxmeter.- 4.6.4 Electronic integrator.- 4.6.5 Nuclear magnetic resonance.- 4.6.6 The Hall effect.- 4.6.7 Magnetoresistance.- 4.6.8 The measurement of pulsed fields.- 4.6.9 Magnetic potentiometer.- 4.6.10 Measurement of induction.- 5 Magnetic scattering of neutrons and magnetic excitations.- 5.1 Properties of the neutron.- 5.2 Sources of neutrons.- 5.3 Powder diffraction.- 5.3.1 Neutron detectors.- 5.3.2 Single detectors.- 5.3.3 Photographic detection of neutrons.- 5.3.4 Multidetectors.- 5.3.5 Monochromators.- 5.4 Inelastic neutron scattering.- 5.4.1 Results of magnon dispersion experiments with neutrons.- 5.5 The polarization of neutron beams.- 5.5.1 By selective Bragg reflection.- 5.5.2 By using supermirrors.- 5.5.3 By using polarizing transmission filters.- 5.6 Engineering applications of neutron scattering.- 5.7 Magnetic excitations and spin waves.- 5.8 Brillouin zones in metals.- 5.8.1 Interaction between conduction electrons and the lattice periodicity.- 5.9 Spin wave resonance.- 6 Antiferromagnetism, ferrimagnetism and non-collinear magnetic order.- 6.1 Antiferromagnetism.- 6.1.1 Magnetization of the sublattices.- 6.1.2 Susceptibility above the Néel temperature.- 6.1.3 Susceptibility below the Néel temperature.- 6.1.4 Perpendicular susceptibility.- 6.1.5 Parallel susceptibility.- 6.1.6 Effect of crystal anisotropy.- 6.1.7 Antiferromagnetism in metals.- 6.2 Ferrimagnetism.- 6.2.1 Structure of the spinel ferrites.- 6.2.2 Two-sublattice theory of ferrimagnetism.- 6.2.3 Susceptibility of the paramagnetic state above the Curie temperature.- 6.2.4 Magnetization below the Curie temperature.- 6.2.5 Saturation magnetic moment of spinel ferrites.- 6.2.6 Hexagonal ferrites.- 6.2.7 Ferrimagnetic garnets.- 6.2.8 Applications of ferrimagnetic oxides.- 6.2.9 Mechanism of magnetic coupling in ferrimagnetic oxides.- 6.3 Helimagnetism.- 6.3.1 Other non-collinear structures.- 6.3.2 Unusual magnetic materials.- 6.4 The rare earth metals.- 6.4.1 Crystal structures.- 6.4.2 Magnetism in rare earths.- 6.4.3 Magnetic structures of the heavier rare earth metals.- 6.4.4 Magnetic structures of the lighter rare earth metals.- 6.5 Spin glasses.- 6.6 Magnetic amorphous alloys.- 6.6.1 Production of metallic glasses.- 6.6.2 Magnetism in amorphous alloys.- 6.7 High-TC superconducting ceramics.- 7 Exchange interactions in magnetism and hyperfine fields.- 7.1 Exchange interactions in magnetism.- 7.1.1 Heisenberg direct exchange between moments localized on atoms.- 7.1.2 Exchange effects between collective electrons.- 7.1.3 Superexchange.- 7.1.4 Indirect exchange by polarization of the conduction electrons.- 7.1.5 Experimental confirmation of the RKKY model.- 7.1.6 Magnetic interactions which differ between different atomic neighbours.- 7.2 Hyperfine interactions in magnetic materials.- 7.2.1 The Mössbauer effect.- 7.2.2 Nuclear magnetic resonance.- 7.2.3 Nuclear contribution to the specific heat capacity.- 8 Domain magnetism.- 8.1 Basic principles.- 8.1.1 Magnetocrystalline anisotropy.- 8.1.2 Magnetostatic energy.- 8.1.3 Domain boundary walls (Bloch walls).- 8.2 Arrangements of domains.- 8.2.1 Experimental observation of magnetic domains.- 8.2.2 Magneto-elastic energy and magnetostriction.- 8.2.3 Magnetization curves and domain wall equilibrium.- 8.3 Single domain particles.- 8.3.1 Superparamagnetism.- 8.4 Soft magnetic materials.- 8.5 Hard magnetic materials.- 8.5.1 Energy product as a figure of merit.- 8.5.2 Neodymium-iron-boron permanent magnets.- 8.6 Thin magnetic films and whiskers.- 8.7 Magnetic bubbles.- 9 Applications of magnetism.- 9.1 Permanent magnets.- 9.1.1 Energy associated with a magnetic field.- 9.1.2 Energy of a permanent magnet.- 9.2 Applications of soft magnetic materials.- 9.3 Magnetic tape recording.- 9.4 Applications of magnetic bubbles.- 9.5 Imaging by nuclear magnetic resonance.- 9.6 Magnetic phase analysis of alloys.- 9.6.1 Ferromagnetic materials.- 9.6.2 Paramagnetic materials.