Itinerant Electron Systems: Magnetism (Ferromagnetism)

P. Mohn 

Technische Universita¨t Wien, Austria

The development of the electron band model (Bloch 1929) paved the way for an understanding of the magnetism of ‘‘itinerant’’ electrons. The first attempts to understand the metallic state were based on the free electron gas model and Pauli (1927) showed that the quenching of the spin can be explained if it is assumed that all the electrons in open shells (conduction electrons) are at least partially free. The Pauli exclusion principle requires that two electrons have to be different in at least one quantum number. For free electrons the only relevant quantum numbers are the spin and the electron momentum k. Since any state with quantum number k can accommodate two electrons, these electrons must have opposite spin so that all spins appear to be compensated. For the susceptibility of the noninteracting (no exchange) gas of free electrons Pauli developed his well-known expression:



Page 340 of the following book

Reference: Concise Encyclopedia of Magnetic and Superconducting Materials

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