Table 71 experimental data for some ferromagnetic

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Unformatted text preview: θ Curie-Weiss law (7.41) θ: paramagnetic Curie temperature > TC 7-21 Fig. 7.12 Reciprocal of the susceptibility per gram of nickel in the neighborhood of the Curie temperature (358 °C). The density is ρ. The dashed line is a linear extrapolation from high temperatures. Table 7.1 Experimental data for some ferromagnetic materials. TC [K] Fe Co Ni gd Dy EuO Eus 1043 1395 629 289 87 69.4 16.5 Θ [K] 1100 1415 649 302 157 78 19 C [K] 2.22 2.24 0.588 Ms(0) [106 A/m] 1.746 1.446 0.510 2.060 2.920 4.68 3.06 1.930 1.240 7-22 Fig. 7.13 spontaneous magnetization of EuO as a function of temperature. ferromagnetic ↔ paramagnetic 2nd order transition - Magnetization (order parameter) changes gradually. - No heat of transformation. 7-23 Mean field approximation for localized electrons Exchange insteraction with neighbouring atoms is treated in a mean field approximation as internal ″exchange field″ or ″molecular field″. Calculation for primitive lattice with unpaired electron with l = 0: ⇒ only spin Exchange energy of i-th lattice atom with Z near...
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This note was uploaded on 01/19/2010 for the course MATERIALS M504 taught by Professor Adelung during the Spring '02 term at Uni Kiel.

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