Magnetic dipole susceptibility

Antiferromagnets have neighboring magnetic dipoles aligned antiparallel there is no net macroscopic moment in zero applied field and the susceptibility is anisotropic below the Neel temperature, TN (See Fig. 128). 

Other materials exhibit a minute positive magnetic susceptibility of appr. 10 6— 10 2. This phenomenon is called paramagnetism = appr. 10 6-10 2 and occurs because dipoles of atoms or molecules in a material align themselves in a magnetic field. Some examples are Al, oxygen 02, platinum, titanium. The magnetic dipoles in the... 

The discontinuity of the interface leads to two contributions to the second order nonlinear polarizability, the electric dipole effect due to the structural discontinuity and the quadrupole type contribution arising from the large electric field gradient at the surface. Under the electric dipole approximation, the nonlinear susceptibility of the centrosymmetric bulk medium 2 is zero. If the higher order magnetic dipole... 

In this equation, d2u) represents the angle of the radiated SH light with respect to the surface normal, 7(co) is the pump intensity, and e(2co) is the polarization at the SH frequency. The vectors e(co) and e(2co) are related to the unit polarization vectors e(co) and e(2co) in medium 2 by Fresnel coefficients. The effective surface nonlinear susceptibility incorporates the surface nonlinear susceptibility x( and the bulk magnetic dipole contributions to the nonlinearity. The result simplifies since, for isotropic media, there are only three nonzero independent elements of xf These are x%, X% = X%.> and XsfL where 1 =... 

It should be apparent that the magnetic susceptibility x of a paramagnetic sample (corrected for diamagnetism) should be infinite at absolute zero (with perfect alignment of the magnetic dipoles, or 100% population of the lowest Zeeman state) and zero at infinite temperature (random alignment of dipoles, equal population of Zeeman states). An obvious expression which embodies these conditions is ... 

The molar magnetic susceptibility, xm> is related to a quantity of more interest to the chemist, the Bohr magneton number (or magnetic dipole moment in Bohr magneton units), designated p. The relationship is ... 

Example 6. For paramagnetic materials the magnetic susceptibility may be measured experimentally and used to give information on the molecular magnetic dipole moment, and hence on the electronic structure of the molecules in the material. The paramagnetic contribution to the molar magnetic susceptibility of a material, xm, is related to the molecular magnetic dipole moment m by the Curie relation... 

If M is the magnetization (magnetic dipole moment per unit volume, analogous to the dielectric polarization P) induced by the field H, the volume magnetic susceptibility x is defined by the equation... 

Magnetic (Natural) Multipoles. Magnetic dipole. In 1905 Langevin, when aiming at an explanation of Curie s law, i.e. of the temperature dependence of magnetic susceptibility in paramagnetics, attributed a priori and classically a permanent magnetic moment to the microsystems. 

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