ferromagnetico

Ferromagnetism is a form of magnetism in which the magnetic moments of atoms in a material tend to align parallel to each other due to the exchange interaction between electrons. Below a characteristic temperature called the Curie temperature, many spins align to produce spontaneous magnetization.

The microscopic origin is the quantum mechanical exchange interaction, which favors parallel alignment of neighboring electron spins. Because of this interaction, ferromagnets typically break rotational symmetry and exhibit magnetic domains: regions where moments are aligned, separated by domain walls. The magnetization of the sample is the vector sum of the domain moments and can be oriented or reoriented by external magnetic fields. When the field is removed, the material often retains a portion of its magnetization, a phenomenon described by hysteresis and characterized by parameters such as saturation magnetization, coercivity, and remanence.

Common ferromagnetic materials include iron (Fe), nickel (Ni), cobalt (Co), and some alloys such as permalloy (NiFe). Rare earth-containing magnets, such as those based on samarium-cobalt or neodymium-iron-boron, are also ferromagnetic and known for high anisotropy and coercivity.

Ferromagnetism contrasts with other magnetic orders such as ferrimagnetism, where sublattice moments align antiparallel but with unequal magnitudes, and antiferromagnetism, where moments align antiparallel with equal magnitudes, resulting in near-zero net magnetization. Above the Curie temperature, ferromagnets become paramagnetic with moments disordered by thermal agitation.

Applications rely on their high magnetization and magnetic response: transformer cores, magnetic recording media, sensors, and permanent magnets used in motors and electronic devices. Understanding ferromagnetism is essential in material science, physics, and engineering. In English the term is ferromagnetic; in Spanish the adjective is ferromagnético.