39 deviations from free electron value if m m order

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Unformatted text preview: diamagnetic contribution. ⇒ 1 χ Landau = − χ Pauli 3 independent of T ! (7.38) (involved calculation even for free electrons) ⇒ Total contribution of conductin electrons χ free electrons = 2 χ Pauli 3 paramagnetic (7.39) Deviations from free electron value if m* ≠ m. Order of magnitude χPauli : + 10-6 Some order of magnitude as diamagnetism of closed shells. ⇒ Metals can be dia- or paramagnetic. Noble metals: diamagnetic, alkali metals except for Cs: paramagnetic. 7-18 Fig. 7.11 Characteristic magnetic susceptibilities of diamagnetic and paramagnetic substances. 7-19 Ferromagnetism Spontaneous magnetization without applied magnetic field. Exchange interaction: Coulomb interaction between electrons depends on spin orientation. : Pauli princilple prevets that electrons approach each other two closely. : Pauli principle does not exclude electrons to be at the same place. Heisenberg model: Exchange interaction described by pairwise nearest-neighbor interaction between spins lokalized at atoms.* Interaction energy: E = -2As1⋅s2 (7.40) A: exchange or coupling constant, depends on overlap of...
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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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