Theory of ferromagnetism

Salvatore Esposito

Publisher: Cambridge University Press

From the book " The Physics of Ettore Majorana: Theoretical, Mathematical, and Phenomenological "

pp 127-146

https://materials-sciences-algerien1970.blogspot.com/2020/04/the-physics-of-ettore-majorana.html

Ettore Majorana

At the October 1930 Solvay conference in Paris, Pauli made a comprehensive review of magnetism, including the intriguing results obtained by Heisenberg [246], Bloch [247, 248], and Slater [249] on the phenomenon of ferromagnetism. That meeting was also attended by Fermi, who, very likely, spread the novel results obtained by those scholars within his group in Rome, and Majorana, used as he was to spending time studying papers published by Heisenberg (and a few other authors), probably became (or was already) aware of his theory of ferromagnetism, in which exchange forces again play a key role in the understanding of the phenomenon. Fermi and his close collaborators never worked or published anything on this subject, but several people visiting the Institute of Physics in Rome in the early 1930s did, including, primarily, Bethe [250], who introduced the famous Bethe ansatz for the case of two interacting spin waves. Other minor (to some extent) contributions came from Inglis [251, 252, 253], who visited Rome in 1932, and from Majorana’s friend Gentile [254], who provided a thorough justification of Bloch’s results on elementary groups (Uebergangsgebiet) of aligned spins inside a ferromagnet [255].

https://sci-hub.tw/https://doi.org/10.1017/CBO9781107358362.006