Anisotropic energy is energy that is directionally specific. The word
anisotropy
Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...
means "directionally dependent", hence the definition. The most common form of anisotropic energy is
magnetocrystalline anisotropy
In physics, a ferromagnetic material is said to have magnetocrystalline anisotropy if it takes more energy to magnetize it in certain directions than in others. These directions are usually related to the principal axes of its crystal lattice. I ...
, which is commonly studied in
ferromagnets
Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials ...
. In ferromagnets, there are islands or domains of atoms that are all coordinated in a certain direction; this spontaneous positioning is often called the "easy" direction, indicating that this is the lowest energy state for these atoms. In order to study magnetocrystalline anisotropy, energy (usually in the form of an
electric current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
) is applied to the domain, which causes the crystals to deflect from the "easy" to "hard" positions. The energy required to do this is defined as the anisotropic energy. The easy and hard alignments and their relative energies are due to the interaction between spin magnetic moment of each atom and the
crystal lattice
In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by
: \mathbf = n_1 \mathbf_1 + n_2 \mathbf_2 + n ...
of the compound being studied.
See also
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Magnetic anisotropy
In condensed matter physics, magnetic anisotropy describes how an object's magnetic properties can be different depending on direction. In the simplest case, there is no preferential direction for an object's magnetic moment. It will respond to ...
References
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Energy (physics)
Orientation (geometry)
Magnetic ordering