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An example of a permanent magnet formed from a ferromagnetic material is a refrigerator magnet. [2] Substances respond weakly to three other types of magnetism—paramagnetism, diamagnetism, and antiferromagnetism—but the forces are usually so weak that they can be detected only by lab instruments.
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.
In classical electromagnetism, magnetization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. Accordingly, physicists and engineers usually define magnetization as the quantity of magnetic moment per unit volume. [1] It is represented by a pseudovector M.
If the magnetic moment is and the volume of the particle is , the magnetization is = / = (,,), where is the saturation magnetization and ,, are direction cosines (components of a unit vector) so + + =. The energy associated with magnetic anisotropy can depend on the direction cosines in various ways, the most common of which are discussed below.
Volume magnetic susceptibility is measured by the force change felt upon a substance when a magnetic field gradient is applied. [8] Early measurements are made using the Gouy balance where a sample is hung between the poles of an electromagnet. The change in weight when the electromagnet is turned on is proportional to the susceptibility.
It is defined as the net magnetic dipole moment per unit volume of that region. The magnetization of a uniform magnet is therefore a material constant, equal to the magnetic moment m of the magnet divided by its volume. Since the SI unit of magnetic moment is A⋅m 2, the SI unit of magnetization M is ampere per meter, identical to that of the ...
Magnetochemistry is concerned with the magnetic properties of chemical compounds and elements. Magnetic properties arise from the spin and orbital angular momentum of the electrons contained in a compound. Compounds are diamagnetic when they contain no unpaired electrons. Molecular compounds that contain one or more unpaired electrons are ...
Magnetic mineralogy is the study of the magnetic properties of minerals. The contribution of a mineral to the total magnetism of a rock depends strongly on the type of magnetic order or disorder. Magnetically disordered minerals (diamagnets and paramagnets) contribute a weak magnetism and have no remanence.