Magnetic moment per unit volume

When a substance is placed in a magnetic field H, it develops a certain amount of magnetization (magnetic moment per unit volume) M given by M = yH, where y is the magnetic susceptibility. The magnetic induction B is defined as... 

Magnetism is an intrinsic property of all materials. When placed in a magnetic field, H, a substance develops an amount of magnetization, M (magnetic moment per unit volume), given by ... 

It is implied in Eq. (38) that, at temperature 0, the value of susceptibility becomes infinite and that there is a finite value of the magnetic moment per unit volume (see Eq. 36), even in the absence of an external field (H = 0) at temperatures lower than 0. Below 0 (a characteristic temperature for a given substance), atom and dipoles (spins) of magnetic materials are ordered. 

We now consider the same solenoid, the volume of which is filled with some isotropic matter. We discuss only the case in which this material is homogenous and multicomponent. A magnetic moment per unit volume, m, is induced in the substance within the solenoid by the current. The net magnetic moment per unit volume is then given by... 

A macroscopic sample (which need not be a bar magnet or current-carrying coil), comprised of a very large number of microscopic (atomic) magnetic moments, can be defined as the magnetization, M, as the net magnetic moment per unit volume (SI units A/m, gauss/cm, or emu/cm in the cgs system) ... 

Equation (5.4) is the Langevin equation of the problem. This equation is now analogous to the equation of motion of a polar molecule under the influence of an electric field [52]. The quantity that directly corresponds to the dipole moment of the polar molecule p. in the Debye theory is the magnetic moment vM of an individual ferrofluid particle, not the magnetization M which is the magnetic moment per unit volume. Equation... 

If A is the number of magnetic moments per unit volume, the magnetisation becomes expressed as... 

When a material is placed in a magnetic field S, a magnetization (magnetic moment per unit volume) Afis induced in the material which is related to HhyM= kH, where K is called the volume susceptibility. Since fl andM have the same dimensions, K is dimensionless. A more useful parameter is the molar susceptibility Xm > defined by... 

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