ALL MATTER Paramagnetic Antiferromagnetic Ferrimagnetic Ferromagnetic e.g. Mno 8.g-1- Fe2 0. FIGURE 36.3 All matter consists of diamagnetic material (atoms having no permanent magnetic dipole moment) aramagnetic material (atoms having magnetic dipole moment). Paramagnetic materials may be further divided into J =oE (current density conductivity X electric field strength) J=P, V (current density volume charge density x carrier velocity) D=EE +P(displacement as function of electric field and polarization) B=H(H M)(magnetic flux density as function of magnetic field strength and magnetization) P=xe E(polarization electric susceptibility x permittivity of free space x electrical field strength) M=x,uH (magnetization magnetic susceptibility x permeability of free space X magnetic field strength) The last two equations relate, respectively, the electric polarization P to the displacement D =E,E and the magnetic moment M to the flux density B=u H. They apply only to "linear"materials, i.e, those for which P is linearly related to E and M to H. For magnetic materials we can say that nonlinear materials are usually of greater practical interest. Dia- and Paramagnetism The phenomenon of magnetism arises ultimately from moving electrical charges(electrons). The movement may be orbital around the nucleus or the other degree of freedom possessed by electrons which, by analogy with the notion of the planets, is referred to as spin. In technologically important materials, i.e., ferromagnetics and ferri magnetics, spin is more important than orbital motion. Each arrow in Fig. 36.3 represents the total spin of an atom. An atom may have a permanent magnetic moment, in which case it is referred to as belonging to a paramagnetic material, or the atom may be magnetized only when in the presence of a magnetic field, in which case it is called diamagnetic. Diamagnetics are magnetized in the opposite direction to that of the applied magnetic field, i.e., they display negative susceptibility(a measure of the induced magnetization per unit of applie magnetic field). Paramagnetics are magnetized in the same direction as the applied magnetic field, i. e, they e 2000 by CRC Press LLC© 2000 by CRC Press LLC J = sE (current density = conductivity 2 electric field strength) J = rvV (current density = volume charge density 2 carrier velocity) D = eoE + P (displacement as function of electric field and polarization) B = mo(H + M) (magnetic flux density as function of magnetic field strength and magnetization) P = ceeoE (polarization = electric susceptibility 2 permittivity of free space 2 electrical field strength) M = cmmoH (magnetization = magnetic susceptibility 2 permeability of free space 2 magnetic field strength) The last two equations relate, respectively, the electric polarization P to the displacement D = eoE and the magnetic moment M to the flux density B = moH. They apply only to “linear” materials, i.e., those for which P is linearly related to E and M to H. For magnetic materials we can say that nonlinear materials are usually of greater practical interest. Dia- and Paramagnetism The phenomenon of magnetism arises ultimately from moving electrical charges (electrons). The movement may be orbital around the nucleus or the other degree of freedom possessed by electrons which, by analogy with the motion of the planets, is referred to as spin. In technologically important materials, i.e., ferromagnetics and ferri￾magnetics, spin is more important than orbital motion. Each arrow in Fig. 36.3 represents the total spin of an atom. An atom may have a permanent magnetic moment, in which case it is referred to as belonging to a paramagnetic material, or the atom may be magnetized only when in the presence of a magnetic field, in which case it is called diamagnetic. Diamagnetics are magnetized in the opposite direction to that of the applied magnetic field, i.e., they display negative susceptibility (a measure of the induced magnetization per unit of applied magnetic field). Paramagnetics are magnetized in the same direction as the applied magnetic field, i.e., they FIGURE 36.3 All matter consists of diamagnetic material (atoms having no permanent magnetic dipole moment) or paramagnetic material (atoms having magnetic dipole moment). Paramagnetic materials may be further divided into ferromagnetics, ferrimagnetics, and antiferromagnetics