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Metals: the Drude and Sommerfeld models | |
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Introduction | |
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What do we know about metals? | |
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The Drude model | |
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Assumptions | |
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The relaxation-time approximation | |
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The failure of the Drude model | |
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Electronic heat capacity | |
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Thermal conductivity and the Wiedemann-Franz ratio | |
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Hall effect | |
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Summary | |
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The Sommerfeld model | |
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The introduction of quantum mechanics | |
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The Fermi-Dirac distribution function | |
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The electronic density of states | |
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The electronic density of states at E [approximate] E[subscript F] | |
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The electronic heat capacity | |
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Successes and failures of the Sommerfeld model | |
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The quantum mechanics of particles in a periodic potential: Bloch's theorem | |
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Introduction and health warning | |
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Introducing the periodic potential | |
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Born-von Karman boundary conditions | |
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The Schrodinger equation in a periodic potential | |
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Bloch's theorem | |
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Electronic bandstructure | |
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The nearly-free electron model | |
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Introduction | |
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Vanishing potential | |
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Single electron energy state | |
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Several degenerate energy levels | |
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Two degenerate free-electron levels | |
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Consequences of the nearly-free-electron model | |
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The alkali metals | |
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Elements with even numbers of valence electrons | |
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More complex Fermi surface shapes | |
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The tight-binding model | |
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Introduction | |
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Band arising from a single electronic level | |
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Electronic wavefunctions | |
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Simple crystal structure | |
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The potential and Hamiltonian | |
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General points about the formation of tight-binding bands | |
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The group IA and IIA metals; the tight-binding model viewpoint | |
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The Group IV elements | |
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The transition metals | |
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Some general points about bandstructure | |
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Comparison of tight-binding and nearly-free-electron bandstructure | |
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The importance of k | |
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hk is not the momentum | |
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Group velocity | |
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The effective mass | |
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The effective mass and the density of states | |
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Summary of the properties of k | |
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Scattering in the Bloch approach | |
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Holes | |
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Postscript | |
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Semiconductors and Insulators | |
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Introduction | |
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Bandstructure of Si and Ge | |
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General points | |
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Heavy and light holes | |
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Optical absorption | |
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Constant energy surfaces in the conduction bands of Si and Ge | |
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Bandstructure of the direct-gap III-V and II-VI semiconductors | |
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Introduction | |
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General points | |
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Optical absorption and excitons | |
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Excitons | |
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Constant energy surfaces in direct-gap III-V semiconductors | |
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Thermal population of bands in semiconductors | |
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The law of mass action | |
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The motion of the chemical potential | |
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Intrinsic carrier density | |
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Impurities and extrinsic carriers | |
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Extrinsic carrier density | |
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Degenerate semiconductors | |
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Impurity bands | |
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Is it a semiconductor or an insulator? | |
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A note on photoconductivity | |
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Bandstructure engineering | |
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Introduction | |
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Semiconductor alloys | |
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Artificial structures | |
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Growth of semiconductor multilayers | |
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Substrate and buffer layer | |
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Quantum wells | |
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Optical properties of quantum wells | |
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Use of quantum wells in opto-electronics | |
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Superlattices | |
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Type I and type II superlattices | |
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Heterojunctions and modulation doping | |
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The envelope-function approximation | |
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Band engineering using organic molecules | |
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Introduction | |
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Molecular building blocks | |
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Typical Fermi surfaces | |
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A note on the effective dimensionality of Fermi-surface sections | |
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Layered conducting oxides | |
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The Peierls transition | |
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Measurement of bandstructure | |
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Introduction | |
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Lorentz force and orbits | |
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General considerations | |
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The cyclotron frequency | |
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Orbits on a Fermi surface | |
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The introduction of quantum mechanics | |
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Landau levels | |
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Application of Bohr's correspondence principle to arbitrarily-shaped Fermi surfaces in a magnetic field | |
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Quantisation of the orbit area | |
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The electronic density of states in a magnetic field | |
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Quantum oscillatory phenomena | |
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Types of quantum oscillation | |
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The de Haas-van Alphen effect | |
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Other parameters which can be deduced from quantum oscillations | |
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Magnetic breakdown | |
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Cyclotron resonance | |
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Cyclotron resonance in metals | |
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Cyclotron resonance in semiconductors | |
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Interband magneto-optics in semiconductors | |
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Other techniques | |
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Angle-resolved photoelectron spectroscopy (ARPES) | |
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Electroreflectance spectroscopy | |
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Some case studies | |
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Copper | |
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Recent controversy: Sr[subscript 2]RuO[subscript 4] | |
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Studies of the Fermi surface of an organic molecular metal | |
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Quasiparticles: interactions between electrons | |
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Transport of heat and electricity in metals and semiconductors | |
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A brief digression; life without scattering would be difficult! | |
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Thermal and electrical conductivity of metals | |
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Metals: the 'Kinetic theory' of electron transport | |
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What do [tau subscript [sigma] and [tau subscript [kappa] represent? | |
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Matthiessen's rule | |
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Emission and absorption of phonons | |
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What is the characteristic energy of the phonons involved? | |
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Electron-phonon scattering at room temperature | |
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Electron-phonon scattering at T [double less-than sign] [theta subscript D] | |
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Departures from the low temperature [sigma] [proportional to] T[superscript -5] dependence | |
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Very low temperatures and/or very dirty metals | |
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Summary | |
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Electron-electron scattering | |
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Electrical conductivity of semiconductors | |
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Temperature dependence of the carrier densities | |
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The temperature dependence of the mobility | |
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Disordered systems and hopping conduction | |
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Thermally-activated hopping | |
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Variable range hopping | |
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Magnetoresistance in three-dimensional systems | |
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Introduction | |
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Hall effect with more than one type of carrier | |
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General considerations | |
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Hall effect in the presence of electrons and holes | |
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A clue about the origins of magnetoresistance | |
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Magnetoresistance in metals | |
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The absence of magnetoresistance in the Sommerfeld model of metals | |
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The presence of magnetoresistance in real metals | |
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The use of magnetoresistance in finding the Fermi-surface shape | |
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The magnetophonon effect | |
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Magnetoresistance in two-dimensional systems and the quantum Hall effect | |
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Introduction: two-dimensional systems | |
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Two-dimensional Landau-level density of states | |
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Resistivity and conductivity tensors for a two-dimensional system | |
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Quantisation of the Hall resistivity | |
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Localised and extended states | |
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A further refinement- spin splitting | |
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Summary | |
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The fractional quantum Hall effect | |
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More than one subband populated | |
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Inhomogeneous and hot carrier distributions in semiconductors | |
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Introduction: inhomogeneous carrier distributions | |
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The excitation of minority carriers | |
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Recombination | |
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Diffusion and recombination | |
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Drift, diffusion and the Einstein equations | |
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Characterisation of minority carriers; the Shockley-Haynes experiment | |
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Hot carrier effects and ballistic transport | |
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Drift velocity saturation and the Gunn effect | |
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Avalanching | |
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A simple resonant tunnelling structure | |
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Ballistic transport and the quantum point contact | |
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Useful terminology in condensed matter physics | |
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Introduction | |
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Crystal | |
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Lattice | |
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Basis | |
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Physical properties of crystals | |
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Unit cell | |
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Wigner-Seitz cell | |
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Designation of directions | |
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Designation of planes; Miller indices | |
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Conventional or primitive? | |
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The 14 Bravais lattices | |
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Derivation of density of states in k-space | |
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Introduction | |
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Density of states | |
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Reading | |
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Derivation of distribution functions | |
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Introduction | |
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Bosons | |
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Fermions | |
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The Maxwell-Boltzmann distribution function | |
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Mean energy and heat capacity of the classical gas | |
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Phonons | |
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Introduction | |
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A simple model | |
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Extension to three dimensions | |
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The Debye model | |
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Phonon number | |
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Summary; the Debye temperature as a useful energy scale in solids | |
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A note on the effect of dimensionality | |
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The Bohr model of hydrogen | |
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Introduction | |
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Hydrogenic impurities | |
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Excitons | |
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Experimental considerations in measuring resistivity and Hall effect | |
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Introduction | |
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The four-wire method | |
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Sample geometries | |
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The van der Pauw method | |
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Mobility spectrum analysis | |
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The resistivity of layered samples | |
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Canonical momentum | |
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Superconductivity | |
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Introduction | |
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Pairing | |
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Pairing and the Meissner effect | |
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List of selected symbols | |
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Solutions and additional hints for selected exercises | |
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Index | |