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4.4: Ising model - Weiss molecular-field theory
https://phys.libretexts.org/Bookshelves/Thermodynamics_and_Statistical_Mechanics/Essential_Graduate_Physics_-_Statistical_Mechanics_(Likharev)/04%3A_Phase_Transitions/4.04%3A_Ising_model_-_Weiss_molecular-field_theory
Thus, below $T_c$ the system is in the ferromagnetic phase, with one of two possible directions of the average spontaneous magnetization, so that the critical (Curie 39 ) temperature, given by Equat...Thus, below $T_c$ the system is in the ferromagnetic phase, with one of two possible directions of the average spontaneous magnetization, so that the critical (Curie 39 ) temperature, given by Equation ( $\ref{72}$ ), marks the transition between the paramagnetic and ferromagnetic phases. (Since the stable minimum value of the free energy $F$ is a continuous function of temperature at $T = T_c$ , this phase transition is continuous.)
6.1: Introduction to Ferromagnetism
https://phys.libretexts.org/Bookshelves/Electricity_and_Magnetism/Book%3A_Applications_of_Maxwells_Equations_(Cochran_and_Heinrich)/06%3A_Ferromagnetism/6.01%3A_Introduction
This tendency is called ”the magnetic pole avoidance principle”. The size of the magnetic domains in the absence of an applied magnetic field depends very strongly on the structure of the material (wh...This tendency is called ”the magnetic pole avoidance principle”. The size of the magnetic domains in the absence of an applied magnetic field depends very strongly on the structure of the material (whether the specimen is a polycrystal or a single crystal), upon the concentration of impurities, and upon the presence of internal stresses.
9.3: Ferromagnets and Electromagnets
https://phys.libretexts.org/Courses/Skyline/Survey_of_Physics/09%3A_Magnetism/9.03%3A_Ferromagnets_and_Electromagnets
All magnetism is created by electric current. Ferromagnetic materials, such as iron, are those that exhibit strong magnetic effects. The atoms in ferromagnetic materials act like small magnets (due to...All magnetism is created by electric current. Ferromagnetic materials, such as iron, are those that exhibit strong magnetic effects. The atoms in ferromagnetic materials act like small magnets (due to currents within the atoms) and can be aligned, usually in millimeter-sized regions called domains. Domains can grow and align on a larger scale, producing permanent magnets. Such a material is magnetized, or induced to be magnetic.
21.2: Magnets
https://phys.libretexts.org/Bookshelves/University_Physics/Physics_(Boundless)/21%3A_Magnetism/21.2%3A_Magnets
There are two type of magnets—ferromagnets that can sustain a permanent magnetic field, and electromagnets produced by the flow of current.
7.5: Landau Theory of Phase Transitions
https://phys.libretexts.org/Bookshelves/Thermodynamics_and_Statistical_Mechanics/Book%3A_Thermodynamics_and_Statistical_Mechanics_(Arovas)/07%3A_Mean_Field_Theory_of_Phase_Transitions/7.05%3A_Landau_Theory_of_Phase_Transitions
Finally, substituting $m=m\ns_+$ gives us a relation between $a$ , $b$ , and $y$ : $y^2=\frac{9}{2}\,ab\ .$ Thus, we have the following: \[\begin{split} a > {y^2\over 4b} \quad &\colon \quad \h...Finally, substituting $m=m\ns_+$ gives us a relation between $a$ , $b$ , and $y$ : $y^2=\frac{9}{2}\,ab\ .$ Thus, we have the following: $\begin{split} a > {y^2\over 4b} \quad &\colon \quad \hbox{1 real root } m=0\\ {y^2\over 4b}>a>{2y^2\over 9b}\quad &\colon\quad \hbox{3 real roots; minimum at } m=0 \\ {2y^2\over 9b} > a \quad &\colon \quad \hbox{3 real roots; minimum at } m={y\over 2b}+\sqrt{\Big({y\over 2b}\Big)^2 - {a\over b}} \end{split}$ The solution $m=0$ lies at a local minim…
22.2: Ferromagnets and Electromagnets
https://phys.libretexts.org/Bookshelves/College_Physics/College_Physics_1e_(OpenStax)/22%3A_Magnetism/22.02%3A_Ferromagnets_and_Electromagnets
All magnetism is created by electric current. Ferromagnetic materials, such as iron, are those that exhibit strong magnetic effects. The atoms in ferromagnetic materials act like small magnets (due to...All magnetism is created by electric current. Ferromagnetic materials, such as iron, are those that exhibit strong magnetic effects. The atoms in ferromagnetic materials act like small magnets (due to currents within the atoms) and can be aligned, usually in millimeter-sized regions called domains. Domains can grow and align on a larger scale, producing permanent magnets. Such a material is magnetized, or induced to be magnetic.
7.3: Ferromagnets and Electromagnets
https://phys.libretexts.org/Courses/Georgia_State_University/GSU-TM-Introductory_Physics_II_(1112)/07%3A_Magnetism/7.03%3A_Ferromagnets_and_Electromagnets
Crucial to the statement that electric current is the source of all magnetism is the fact that it is impossible to separate north and south magnetic poles. (This is far different from the case of posi...Crucial to the statement that electric current is the source of all magnetism is the fact that it is impossible to separate north and south magnetic poles. (This is far different from the case of positive and negative charges, which are easily separated.) A current loop always produces a magnetic dipole—that is, a magnetic field that acts like a north pole and south pole pair.

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