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Magnetic structure
The term magnetic structure of a material pertains to the ordered arrangement of magnetic spins, typically within an ordered crystallographic lattice. Its study is a branch of solid-state chemistry.
==Magnetic structures==
Most solid materials are Pauli-paramagnetic. These materials either do not have electron spins or these spins are not ordered unless an external field induces some non-random orientation. Such materials are not considered to 'have' a magnetic structure. This is different for ferro-, ferri- and antiferromagnetic materials. They differ in the relative ordering of their spins within the lattice. In some ferromagnetic cases the structure may be relatively simple in that all spins point in the same direction, or at least that would be the case at very low temperatures. Towards higher temperatures there will be more and more 'rebellious' spins defying the order of the magnetic structure and at a certain temperature the order will break down and the spins will point in random directions. In some materials the pattern in which the spins order is much more complicated. In antiferromagnetic materials spins point in opposite directions so that the overall magnetic moment is zero. However, this is not necessarily achieved by a simple up and down pattern. Much more complicated structures can arise. At times one can recognize layers in which all spins point in one direction (as in a ferromagnet) but in the next layer they point in the opposite direction giving an overall antiferromagnetic arrangement. The possible number of arrangements is very large and can include spirals, clusters, tetrahedra etc.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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