Magneton, Bohr

What goes on at the microscopic level inside a material that determines its magnetic properties MacroscopicaUy, we identified magnetism with current flow or moving charge. 

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Cobalt difluoride [10026-17-2] C0F2, is a pink solid having a magnetic moment of 4, 266 x 10 J/T (4.6 Bohr magneton) (1) and closely resembling the ferrous (Fep2) compounds. Physical properties are Hsted in Table 1. Cobalt(II) fluoride is highly stable. No decomposition or hydrolysis has been observed in samples stored in plastic containers for over three years. 

Here NO plays a role similar to that of Cl or CN in complexes, and may appropriately be called electronegative.) This 32 complex should have a magnetic moment of 2.83 Bohr magnetons, a value in excellent agreement with the observed 2.81. 

S is the spin quantum number. The expected magnetic moments for a sextet and a doublet state are 5.91 and 1.73 respectively, measured in Bohr magnetons. The values calculated from the observed paramagnetic susceptibilities of the crystals are 5.88 for (NH aFeFg and 2.0 for... 

The multiplicity can be determined from the experimental values of the magnetic susceptibility, the magnetic moment in Bohr magnetons being equal to 2 VS(S + l), in which S is the spin quantum number. (The multiplicity is 2S + 1.) The moments for 22 and 62 are 1.73 and 5.91, respectively. The experimental values for K3Fe(CN)6 and (NH jFeF are 2.0 and 5.88, respectively, so that the bonds in the [FefCN ] ion are electron-pair bonds, and those in [FeFe]a are ionic. 

Values 3.8 to 4.0 Bohr magnetons are observed for iron-group ions with this configuration. 

The values for the atomic saturation magnetization at the absolute zero, ferromagnetic metals iron, cobalt, and nickel are 2.22, 1.71, and 0.61 Bohr magnetons per atom, respectively.9 These numbers are the average numbers of unpaired electron spins in the metals (the approximation of the g factor to 2 found in gyromagnetic experiments shows that the orbital moment is nearly completely quenched, as in complex ions containing the transition elements). 

Fig. 1. Comparison of experimental values (solid curves) and predicted values (dashed lines) of the saturation ferromagnetic moment per atom, in Bohr magnetons, for Fe-Co, Co-Ni, and Ni-Cu alloys. The short vertical lines indicate change in crystal structure (from Ref. (2)).

Figure 2. Plot of relative magnetization, a/Os ns a function of H/T. (a) A paramagnetic system Is characterized by an effective magnetic moment, with a Bohr Magneton number vlO per Ion, and by the absence of hysteresis. Paramagnetic saturation occurs at very high "H/T" == 10 Oe K"l. (b) l.angevln curve for S.P. clusters, (c) Part of a ferromagnetic hysteresis curve.

Figure 4. Magnetization (Bohr magnetons/iron atom) as a function of temperature for ZSM-5 (11.1% Fe) (H 6300 Oe (V) reduced (A) carbided (0) used).

Since the units of L are those of h, we have defined in equation (5.81) the Bohr magneton /tb as... 

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