Magnetic ordering

thumb|right|Electric displacement field of a ferroelectric material as the [[electric field is first decreased, then increased. The curves form a hysteresis loop.]] Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Such a system is called hysteretic. Plots of a single component of the moment often form a loop or hysteresis curve, where there are different values of one variable depending on the direction of change of another variab

thumb|Antiferromagnetic ordering thumb|Magnetic orders : comparison between ferro, antiferro and ferrimagnetism

Magnetostriction is a property of magnetic materials that causes them to change their shape or dimensions during the process of magnetization. The variation of materials' magnetization due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation value, λ. The effect was first identified in 1842 by James Joule when observing a sample of iron.

thumb|Ferrimagnetic ordering thumb|Magnetic orders: comparison between ferro, antiferro and ferrimagnetism thumb|Ferrite magnets. Ferrite (magnet)|Ferrite, a [[ceramic compound, is one of the most common examples of a ferrimagnetic material.]] 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. This can, for example, occur when the populations consist of different atoms or ions (such as Fe2+ and Fe3+).

Superparamagnetism is a form of magnetism which appears in small ferromagnetic or ferrimagnetic nanoparticles. In sufficiently small nanoparticles, magnetization can randomly flip direction under the influence of temperature. The typical time between two flips is called the Néel relaxation time. In the absence of an external magnetic field, when the time used to measure the magnetization of the nanoparticles is much longer than the Néel relaxation time, their magnetization appears to be on average zero; they are said to be in the superparamagnetic state. In this state, an external magnetic fie

Magnetoresistance is the tendency of a material (often ferromagnetic) to change the value of its electrical resistance in an externally-applied magnetic field. There are a variety of effects that can be called magnetoresistance. Some occur in bulk non-magnetic metals and semiconductors, such as geometrical magnetoresistance, Shubnikov–de Haas oscillations, or the common positive magnetoresistance in metals. Other effects occur in magnetic metals, such as negative magnetoresistance in ferromagnets or anisotropic magnetoresistance (AMR). Finally, in multicomponent or multilayer systems (e.g. mag

physical law that magnetization of a paramagnetic sample is directly proportional to the external magnetic field and inversely proportional to the absolute temperature

material state characterized by magnetic disorder

a spectroscopic technique to probe the magnetization of ferromagnetic materials

phenomenon where atoms tend to stick to non-trivial positions; set of degrees of freedom incompatible with the space occupied

thumb|An example of an altermagnetic ordering, with the direction of the spins and the spatial orientation of the atoms alternating on the neighbouring sites in the crystal. In condensed matter physics, altermagnetism is a type of persistent magnetic state in ideal crystals. Altermagnetic structures are collinear and crystal-symmetry compensated, resulting in zero net magnetisation. Unlike in an ordinary collinear antiferromagnet, another magnetic state with zero net magnetization, the electronic bands in an altermagnet are not Kramers degenerate, but instead depend on the wavevector in a spin

magnetic material under special conditions

statistical model in quantum mechanics of magnetic materials

magnetic propagations

describing the precessional motion of magnetization in a solid

directional dependence of substances' magnetic susceptibilities

Metamagnetism is a sudden (often, dramatic) increase in the magnetization of a material with a small change in an externally applied magnetic field. The metamagnetic behavior may have quite different physical causes for different types of metamagnets. Some examples of physical mechanisms leading to metamagnetic behavior are:

Micromagnetics is a field of physics dealing with the prediction of magnetic behaviors at sub-micrometer length scales. The length scales considered are large enough for the atomic structure of the material to be ignored (the continuum approximation), yet small enough to resolve magnetic structures such as domain walls or vortices.

Piezomagnetism is a phenomenon observed in some antiferromagnetic and ferrimagnetic crystals. It is characterized by a linear coupling between the system's magnetic polarization and mechanical strain. In a piezomagnetic material, one may induce a spontaneous magnetic moment by applying mechanical stress, or a physical deformation by applying a magnetic field.

Magnonics is an emerging field of modern magnetism, which can be considered a subfield of modern solid-state physics. Magnonics combines the study of waves and magnetism. Its main aim is to investigate the behaviour of spin waves in nano-structured elements. In essence, spin waves are a propagating re-ordering of the magnetisation in a material and arise from the precession of magnetic moments. Magnetic moments arise from the orbital and spin moments of the electron; most often, it is this spin moment that contributes to the net magnetic moment.

direction dependence of magnetization in a crystal

thumb|Lorentz Transmission electron microscopy|TEM image of helical spin stripes in [[iron germanide (FeGe) at 90 K]] Helimagnetism is a form of magnetic ordering where spins of neighbouring magnetic moments arrange themselves in a spiral or helical pattern, with a characteristic turn angle of somewhere between 0 and 180 degrees. It results from the competition between ferromagnetic and antiferromagnetic exchange interactions. It is possible to view ferromagnetism and antiferromagnetism as helimagnetic structures with characteristic turn angles of 0 and 180 degrees respectively. Helimagnetic o

concept in statistical physics

ordered arrangement of magnetic spins in a material

magnetic phase transition in α-Fe2O3 hematite

Mictomagnetism is a spin system in which various exchange interactions are mixed. It is observed in several kinds of alloys, including Cu–Mn, Fe–Al and Ni–Mn alloys. Cooled in zero magnetic field, these materials have low remanence and coercivity. Cooled in a magnetic field, they have much larger remanence, and the hysteresis loop is shifted in the direction opposite to the field (an effect similar to exchange bias).

physical phenomenon