In the physical sciences, a multilayer or stratified medium is a stack of different
thin film
A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many ap ...
s. Typically, a multilayer is man made for a specific purpose. Since layers are thin with respect to some relevant length scale,
interface effects are much more important than in bulk materials, giving rise to novel physical properties.
The term "multilayer" is ''not'' an extension of "
monolayer A monolayer is a single, closely packed layer of atoms, molecules, or cells. In some cases it is referred to as a self-assembled monolayer. Monolayers of layered crystals like graphene and molybdenum disulfide are generally called 2D materials.
...
" and "
bilayer
A bilayer is a double layer of closely packed atoms or molecules.
The properties of bilayers are often studied in condensed matter physics, particularly in the context of semiconductor devices, where two distinct materials are united to form jun ...
", which describe a ''single'' layer that is one or two molecules thick. A multilayer medium rather consists of several thin films.
Examples
An
optical coating
An optical coating is one or more thin layers of material deposited on an optical component such as a lens, prism or mirror, which alters the way in which the optic reflects and transmits light. These coatings have become a key technology in th ...
, as used for instance in a
dielectric mirror
A dielectric mirror, also known as a Bragg mirror, is a type of mirror composed of multiple thin layers of dielectric material, typically deposited on a substrate of glass or some other optical material. By careful choice of the type and thickne ...
, is made of several layers that have different
refractive index
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.
The refractive index determines how much the path of light is bent, or ...
es.
Giant magnetoresistance
Giant magnetoresistance (GMR) is a quantum mechanical magnetoresistance effect observed in multilayers composed of alternating ferromagnetic and non-magnetic conductive layers. The 2007 Nobel Prize in Physics was awarded to Albert Fert and Peter ...
is a macroscopic quantum effect observed in alternating ferromagnetic and non-magnetic conductive layers.
See also
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Transfer-matrix method (optics)
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Dielectric mirror
A dielectric mirror, also known as a Bragg mirror, is a type of mirror composed of multiple thin layers of dielectric material, typically deposited on a substrate of glass or some other optical material. By careful choice of the type and thickne ...
References
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Thin films
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