Demagnetizing field

The demagnetizing field, also called the stray field (outside the magnet), is the <a href="/facts/Magnetic_field/Ta8Ev588">magnetic field</a> (H-field) generated by the <a href="/facts/Magnetization/zxrtXzTN">magnetization</a> in a <a href="/facts/Magnet/vvrg6VSk">magnet</a>. The total magnetic field in a region containing magnets is the sum of the demagnetizing fields of the magnets and the magnetic field due to any <a href="/facts/Free_current/zxrtXzTN">free currents</a> or <a href="/facts/Displacement_current/l3C1QQ1q">displacement currents</a>. The term demagnetizing field reflects its tendency to act on the magnetization so as to reduce the total <a href="/facts/Magnetic_moment/VpAQKJtr">magnetic moment</a>. It gives rise to shape anisotropy in <a href="/facts/Ferromagnets/fH3HFnSl">ferromagnets</a> with a <a href="/facts/Single-domain_(magnetic)/0LLtyIbC">single magnetic domain</a> and to <a href="/facts/Magnetic_domains/f7KTN10R">magnetic domains</a> in larger ferromagnets.
The demagnetizing field of an arbitrarily shaped object requires a numerical solution of <a href="/facts/Poisson%2527s_equation/Pr8zkCXB">Poisson's equation</a> even for the simple case of uniform magnetization. For the special case of <a href="/facts/Ellipsoid/pe9vm0Sh">ellipsoids</a> (including infinite cylinders) the demagnetization field is linearly related to the magnetization by a geometry dependent constant called the demagnetizing factor. Since the magnetization of a sample at a given location depends on the total magnetic field at that point, the demagnetization factor must be used in order to accurately determine how a magnetic material responds to a magnetic field. (See <a href="/facts/Magnetic_hysteresis/KchYJC1p">magnetic hysteresis</a>.)

Demagnetizing field open-in-new

Demagnetizing field