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Saturation is most clearly seen in the magnetization curve (also called BH curve or hysteresis curve) of a substance, as a bending to the right of the curve (see graph at right). As the H field increases, the B field approaches a maximum value asymptotically , the saturation level for the substance.
The downward curve after saturation, along with the lower return curve, form the main loop. The intercepts h c and m rs are the coercivity and saturation remanence. Magnetic hysteresis occurs when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles align themselves with it.
Magnetization (J) or flux density (B) curve as a function of magnetic field intensity (H) in ferromagnetic material. The inset shows Barkhausen jumps. Origin of the Barkhausen noise: as a domain wall moves it gets caught on a defect in the crystal lattice , then "snaps" past it, creating a sudden change in the magnetic field.
Electrical steel is an iron alloy which may have from zero to 6.5% silicon (Si:5Fe). Commercial alloys usually have silicon content up to 3.2% (higher concentrations result in brittleness during cold rolling). Manganese and aluminum can be added up to 0.5%. [1]
Typically the coercivity of a magnetic material is determined by measurement of the magnetic hysteresis loop, also called the magnetization curve, as illustrated in the figure above. The apparatus used to acquire the data is typically a vibrating-sample or alternating-gradient magnetometer. The applied field where the data line crosses zero is ...
The curves form a hysteresis loop. Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of the moment often form a loop or hysteresis curve, where there are ...
These losses are called hysteresis. The energy lost per cycle is proportional to the area of the hysteresis loop in the BH graph. To minimize this loss, magnetic cores used in transformers and other AC electromagnets are made of "soft" low coercivity materials, such as silicon steel or soft ferrite.
This is one of the most popular models of magnetic hysteresis. Its main advantage is the fact that this model enables connection with physical parameters of the magnetic material. [2] Jiles–Atherton model enables calculation of minor and major hysteresis loops. [1] The original Jiles–Atherton model is suitable only for isotropic materials. [1]