We present and analyze in detail an unknown theory of ferromagnetism developed by Ettore Majorana as early as the beginnings of 1930s, substantially different in the methods employed from the well-known Heisenberg theory of 1928 (and from later formulations by Bloch and others). Similarly to this, however, it describes Successfully the main features of ferromagnetism, although the key equation for the spontaneous mean magnetization and the expression for the Curie temperature are different from those deduced in the Heisenberg theory (and in the original phenomenological Weiss theory). The theory presented here contains also a Peculiar prediction for the number of nearest neighbors required to realize ferromagnetism, which avoids the corresponding arbitrary assumption made by Heisenberg on the basis of known (at that time) experimental observations. Some applications of the theory (linear chain, triangular chain, etc.) are, as well, considered. (C) 2008 Elsevier Inc. All rights reserved.

A theory of ferromagnetism by Ettore Majorana / Esposito, S. - In: ANNALS OF PHYSICS. - ISSN 0003-4916. - 324:1(2009), pp. 16-29. [10.1016/j.aop.2008.07.005]

A theory of ferromagnetism by Ettore Majorana

Esposito S
2009

Abstract

We present and analyze in detail an unknown theory of ferromagnetism developed by Ettore Majorana as early as the beginnings of 1930s, substantially different in the methods employed from the well-known Heisenberg theory of 1928 (and from later formulations by Bloch and others). Similarly to this, however, it describes Successfully the main features of ferromagnetism, although the key equation for the spontaneous mean magnetization and the expression for the Curie temperature are different from those deduced in the Heisenberg theory (and in the original phenomenological Weiss theory). The theory presented here contains also a Peculiar prediction for the number of nearest neighbors required to realize ferromagnetism, which avoids the corresponding arbitrary assumption made by Heisenberg on the basis of known (at that time) experimental observations. Some applications of the theory (linear chain, triangular chain, etc.) are, as well, considered. (C) 2008 Elsevier Inc. All rights reserved.
2009
A theory of ferromagnetism by Ettore Majorana / Esposito, S. - In: ANNALS OF PHYSICS. - ISSN 0003-4916. - 324:1(2009), pp. 16-29. [10.1016/j.aop.2008.07.005]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/899805
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