Solid state physics

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The solid-state physics deals with the physics of matter in the solid state of aggregation . Crystalline solids are of particular importance . These are those that have a translational symmetry (periodic) structure, since this translational symmetry drastically simplifies the physical treatment of many phenomena or makes it possible in the first place. For this reason, the model of the ideal crystal lattice is often used even when the periodicity condition is only met to a very limited extent, for example only very locally. The deviation from the strict periodicity is then taken into account through corrections.

Superconductors belong to the research area of ​​solid state physics.

Appearances of solids

Crystalline solids

Four examples of crystalline solids: coltan , cassiterite , wolframite and gold

The physics of crystalline solids (crystal physics ) deals with solids that have a periodic structure.

Partly crystalline substance

A partially crystalline substance, which has a certain short-range order in the range of 4.5–6  Å , but in contrast to a crystal, but no pronounced long-range order , is a paracrystal .

Amorphous solids

Metallic glass is an amorphous solid.

The physics of amorphous solids deals with solids that have no long-range order.

Interface physics

Interface physics deals with the special features of interfaces, while surface physics is a special case of interface physics at interfaces with a vacuum . The physical properties of the few atomic layers near the interface differ due to the non-periodic boundary conditions from the physics inside, which is also called volume solid .

States of order in solids

When describing the regularity in the structure of the solid, one considers on the one hand the short-range order in the range of a few nanometers and on the other hand the long-range order, which relates to far greater distances.

Local to long-range order in solids
Status Range of order example
amorphous (local order) next and next but one particle Glass
nanocrystalline Nanometer Paracrystal
micro crystalline Micrometer quartz
polycrystalline millimeter Polycrystalline diamond
monocrystalline (long-range order) centimeter monocrystalline ingots

Subject areas of modern research

Investigation methods in solid state physics

In solid-state physics, similar to solid-state chemistry , a number of methods are used to investigate the properties of functional materials in particular and to understand their properties in the depth of the structure. This is important in many modern applications, such as electronics , computer chips , semiconductor technology , solar cells , batteries , lighting , metals , insulators . The important methods include:

The X-ray diffraction utilizes the effect of the diffraction of X-rays at crystal lattices to study the symmetry properties of solids, in 230 different so-called space groups are present. For this purpose X-ray diffractometer used. Materials can also be examined for their quality and purity as well as the crystallite size.

The neutron diffraction uses the same diffraction effect with the same basic principles as the X-ray diffraction, however, instead of X-rays neutrons used mostly in research nuclear reactors are provided. Due to the different wave properties of the massive neutron compared to the X-rays, the diffractometers are very large, usually several meters. In addition to the 230 space groups, it is particularly possible to study magnetic orders in crystals. With the addition of the spin , the magnetic space groups expand to 1651.

With magnetometers in particular the magnetic properties are examined. One of the common methods is the SQUID in conjunction with cryostats to determine the different types of magnetism and to identify the magnetic phase diagrams .

With tracer diffusion , the diffusion of atoms and ions in crystals is investigated. This is important in doping processes or for the temperature stability of materials, e.g. B. in the solid oxide fuel cell .

While the previous methods measure macroscopic properties, the methods of nuclear solid-state physics can be used to investigate local structures at the atomic level by using atomic nuclei as a probe. This z. B. the size of the magnetic field can be measured at the location of the core or local defects in the crystal lattice. Another important parameter are electrical field gradients , with which the local structure and its change with temperature changes or changes in the concentration of certain components in the material are researched. Measurement methods are e.g. B. Mössbauer spectroscopy , disturbed gamma-gamma angle correlation , nuclear magnetic resonance spectroscopy or muon spin spectroscopy .


  • Gerd Czycholl: Theoretical solid state physics. From classic models to modern research topics . 3. Edition. Springer, 2008, ISBN 978-3-540-74790-1 .
  • Joseph Callaway: Quantum Theory of Solid State . 1st edition. Academic Press, New York and London, ISBN 978-0-12-155201-5 .

Individual evidence

  1. M. Popescu, H. Bradaczek: Microparacrystalline model for medium-range order in non-crystalline chalcogenides . In: Journal of Optoelectronics and Advanced Materials . tape 3 , no. 2 , June 2001, p. 249–254 ( [PDF; 437 kB ; accessed on September 21, 2016]).
  2. Horst-Günter Rubahn, Frank Balzer: Laser applications on hard and soft surfaces. Springer-Verlag, 2005, ISBN 978-3-519-00490-5 , p. 1 ( limited preview in Google book search).
  3. Andreas Battenberg (Red.): Superconductivity in the land of "heavy electrons". Interplay of electronic magnetism, nuclear spins and superconductivity. In: News from the Physics Department. Physics DepartmentTechnical University of Munich , February 1, 2016, accessed on September 19, 2016 .