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The magnetization that occurs below T C is an example of the "spontaneous" breaking of a global symmetry, a phenomenon that is described by Goldstone's theorem. The term "symmetry breaking" refers to the choice of a magnetization direction by the spins, which have spherical symmetry above T C, but a preferred axis (the magnetization direction ...
A magnetic moment which is present even in the absence of the external magnetic field is called spontaneous magnetization. Materials with this property are known as ferromagnets, such as iron, nickel, and magnetite. However, when these materials are heated up, at a certain temperature they lose their spontaneous magnetization, and become ...
A ferrimagnetic material is a material that has populations of atoms with opposing magnetic moments, as in antiferromagnetism, but these moments are unequal in magnitude, so a spontaneous magnetization remains. [1] This can for example occur when the populations consist of different atoms or ions (such as Fe 2+ and Fe 3+).
Ferromagnetism: A state of matter with spontaneous magnetization. Antiferromagnetism: A state of matter in which the neighboring spin are antiparallel with each other, and there is no net magnetization. Ferrimagnetism: A state in which local moments partially cancel. Altermagnetism: A state with zero net magnetization and spin-split electronic ...
When a magnetic field is absent the material has spontaneous magnetization which is a result of the ordered magnetic moments; that is, for ferromagnetism, the atoms are symmetrical and aligned in the same direction creating a permanent magnetic field.
Ferromagnetic materials still has a spontaneous magnetization at low fields (below the Curie-temperature), and the susceptibility must then instead be explained by Curie–Weiss law. Two-state case (spin-1/2)
The other is ferrimagnetism, where some magnetic moments point in the opposite direction but have a smaller contribution, so spontaneous magnetization is present. [ 4 ] [ 5 ] : 28–29 In the special case where the opposing moments balance completely, the alignment is known as antiferromagnetism ; antiferromagnets do not have a spontaneous ...
The concept of a magnon was introduced in 1930 by Felix Bloch [1] in order to explain the reduction of the spontaneous magnetization in a ferromagnet.At absolute zero temperature (0 K), a Heisenberg ferromagnet reaches the state of lowest energy (so-called ground state), in which all of the atomic spins (and hence magnetic moments) point in the same direction.