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In physics and materials science, the Curie temperature (), or Curie point, is the temperature at which certain materials lose their permanent magnetic properties, to be replaced by induced magnetism. The Curie temperature is named after Pierre Curie, who showed that magnetism was lost at a critical temperature. The force of magnetism is determined by the magnetic moment, a dipole moment within an atom which originates from the angular momentum and spin of electrons. Materials have different structures of intrinsic magnetic moments that depend on temperature; the Curie temperature is the critical point at which a material's intrinsic magnetic moments change direction. Permanent magnetism is caused by the alignment of magnetic moments and induced magnetism is created when disordered magnetic moments are forced to align in an applied magnetic field. For example, the ordered magnetic moments (ferromagnetic, Figure 1) change and become disordered (paramagnetic, Figure 2) at the Curie temperature. Higher temperatures make magnets weaker, as spontaneous magnetism only occurs below the Curie temperature. Magnetic susceptibility only occurs above the Curie Temperature and can be calculated from the Curie-Weiss Law which is derived from Curie's Law. In analogy to ferromagnetic and paramagnetic materials, the Curie temperature can also be used to describe the phase transition between ferroelectricity and paraelectricity. In this context, the order parameter is the ''electric'' polarisation that goes from a finite value to zero when the temperature is increased above the Curie temperature. == Magnetic moments == Magnetic moments are permanent dipole moments within the atom which are made up from electrons' angular momentum and spin. Electrons inside atoms contribute magnetic moments from their own angular momentum and from their orbital momentum around the nucleus. Magnetic moments from the nucleus are insignificant in contrast to magnetic moments from electrons. Thermal contribution will result in higher energy electrons causing disruption to their order and alignment between dipoles to be destroyed. Ferromagnetic, paramagnetic, ferrimagnetic and antiferromagnetic materials have different structures of intrinsic magnetic moments. It is at a material's specific Curie Temperature where they change properties. The transition from antiferromagnetic to paramagnetic (or vice versa) occurs at the Néel Temperature which is analogous to Curie Temperature. File:Diagram of Ferromagnetic Magnetic Moments.png|Ferromagnetism The magnetic moments in a ferromagnetic material. The moments are ordered and of the same magnitude in the absence of an applied magnetic field. File:Diagram of Paramagnetic Magnetic Moments.png|Paramagnetism The magnetic moments in a paramagnetic material. The moments are disordered in the absence of an applied magnetic field and ordered in the presence of an applied magnetic field. File:Diagram of Ferrimagnetic Magnetic Moments.png|Ferrimagnetism The magnetic moments in a ferrimagnetic material. The moments are aligned oppositely and have different magnitudes due to being made up of two different ions. This is in the absence of an applied magnetic field. File:Diagram of Antiferromagnetic Magnetic Moments.png|Antiferromagnetism The magnetic moments in an antiferromagnetic material. The moments are aligned oppositely and have the same magnitudes. This is in the absence of an applied magnetic field. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Curie temperature」の詳細全文を読む スポンサード リンク
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