The Curie point is a term in physics and materials science, named after Pierre Curie (1859-1906), and refers to a characteristic property of a ferromagnetic material. A Superconductor demonstrating the Meissner Effect Physics (from the Greek, φυσικός (physikos), natural, and φύσις (physis), nature) is the science of the natural world dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces. ... The Materials Science Tetrahedron, which often also includes Characterization at the center Materials science is the multidisciplinary field relating the performance and function of matter in any and all applications to its micro, nano, and atomic-structure, and vice versa. ... Pierre Curie Pierre Curie (May 15, 1859 – April 19, 1906) was a pioneer in the study of crystallography, magnetism, piezoelectricity and radioactivity. ... A ferromagnet is a piece of ferromagnetic material, in which the microscopic magnetized regions, called domains, have been aligned by an external magnetic field (e. ...

The Curie point, or Curie temperature, T_c, of a ferromagnetic material, is the temperature above which it loses its characteristic ferromagnetic ability: the ability to possess a net (spontaneous) magnetization in the absence of an external magnetic field. Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ... This article needs to be cleaned up to conform to a higher standard of quality. ... It has been suggested that Magnetic field density be merged into this article or section. ...

At temperatures below the Curie point the magnetic moments are partially aligned within magnetic domains in ferromagnetic materials. As the temperature is increased from below the Curie point, thermal fluctuations increasingly destroy this alignment, until the net magnetization becomes zero at and above the Curie point. Above the Curie point, the material is purely paramagnetic. In physics, the magnetic moment of an object is a vector relating the aligning torque in a magnetic field experienced by the object to the field vector itself. ... Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ... Paramagnetism is the tendency of the atomic magnetic dipoles, due to quantum-mechanical spin, in a material that is otherwise non-magnetic to align with an external magnetic field. ...

At temperatures below the Curie point, an applied magnetic field has a paramagnetic effect on the magnetization, but the combination of paramagnetism with ferromagnetism leads to the magnetization following a hysteresis curve with the applied field strength. The destruction of magnetization at the Curie temperature is a second-order phase transition and a critical point where the magnetic susceptibility is theoretically infinite. Hysteresis is a property of systems (usually physical systems) that do not instantly follow the forces applied to them, but react slowly, or do not return completely to their original state: that is, systems whose states depend on their immediate history. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... Chemistry In chemistry, a critical point is the conditions ( temperature, pressure) at which the liquid state of the matter ceases to exist. ... In electrical engineering, the magnetic susceptibility is the degree of magnetization of a material in response to a magnetic field. ...

See ferromagnetism for a list of ferromagnetic materials and their Curie temperatures. Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ...

The effect is primarily used in magneto-optical storage media, where it is used for erasing and writing of new data. Famous example include the Sony Minidisc format, as well as the defunct CD-MO format. Magneto-optical disc A Magneto-optical disc and the numerous rectangles on its surface A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon magneto-optical discs. ... The Sony MZ1 MiniDisc player, the first to hit the market in 1992. ... Compact Disc ReWritable (CD-RW) is a rewritable optical disc format. ...

Other uses include use temperature control in soldering irons, and, in generally, where a temperature-controlled magnetization is desirable. Using a soldering iron. ...

Curie temperature in piezoelectric materials

In analogy to ferromagnetic materials, the Curie temperature is also used in piezoelectric materials to describe the temperature above which the material loses its spontaneous polarization and piezoelectric characteristics. In lead zirconate titanate, the material is tetrahedral below T_c and the unit cell contains a displaced central cation and hence a net dipole moment. Above T_c, the material is cubic and the central cation is no longer displaced from the centre of the unit cell. Hence, there is no net dipole moment and no spontaneous polarization. Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ... Lead zirconium titanate (PZT, also Lead zirconate titanate) is a ceramic perovskite material that shows a marked piezoelectric effect - that is, it develops a voltage difference across two of its faces when compressed, and ferroelectric effect. ...

See also

• Ferroelectric effect
• Néel temperature