# Solid-state physics

**Solid-state physics**, the largest branch of condensed matter physics, is the study of rigid matter, or solids. The bulk of solid-state physics theory and research is focused on crystals, largely because the periodicity of atoms in a crystal--its defining characteristic--facilitates mathematical modeling, and also because crystalline materials often have electrical, magnetic, optical, or mechanical properties that can be exploited for engineering purposes.

The framework of most solid-state physics theory is the Schrödinger (wave) formulation of non-relativistic quantum mechanics. Bloch's Theorem, which characterizes the wavefunctions of electrons in a periodic potential, is an important starting point for much analysis. Since Bloch's Theorem applies only to periodic potentials, and since unceasing random movements of atoms in a crystal disrupt periodicity, Bloch's Theorem is only an approximation, but it has proven to be a tremendously valuable approximation, without which most solid-state physics analysis would be intractable. Deviations from periodicity are treated by quantum mechanical perturbation theory.

### Topics

- Amorphous solid
- Crystal structure
- Electronic structure
- bandgap
- Bloch waves (electron waves in a lattice)
- conduction band
- effective mass
- electron hole
- Fermi gas
- Fermi liquid
- exciton
- valence band

- Electronic transport
- Bloch oscillations
- Drude model
- electrical conduction
- Hall effect
- magnetoresistance

- Mechanical properties
- Debye model of specific heat
- elasticity
- Mossbauer effect
- phonons (lattice vibrations)

- Optical properties

### External links and references

- Online textbook:
*Introduction to Modern Solid State Physics*by Yuri M. Galperin.

General subfields within physics
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Classical mechanics | Condensed matter physics | Continuum mechanics | Electromagnetism | General relativity | Particle physics | Quantum field theory | Quantum mechanics | Solid state physics | Special relativity | Statistical mechanics | Thermodynamics |