Summary
The self-consistent method in quantum field theory is applied to the itinerant-electron ferromagnet. The magnon as a bound state of electrons is studied by using Bethe-Salpeter equations in the pair approximation. The spin rotation of electrons is induced by anE 2-symmetry transformation of magnons and quasi-electrons which is different from a rotation. A simple derivation of the low-energy theorem is discussed.
Riassunto
Si applica il metodo autoconsistente della teoria quantistica dei campi al ferromagnete con elettrone mobile. Si studia il magnone come stato legato di elettroni facendo uso dell’equazione di Bethe-Salpeter nell’approssimazione delle coppie. La rotazione dello spin degli elettroni è introdotta da una trasformazione della simmetria diE 2 dei magnoni e dei quasi elettroni che è diversa da una rotazione. Si discute una semplice deduzione del teorema di bassa energia.
Резюме
Самосогласованный метод в квантовой теории поля применяется к исследованию ферромагнетика со «странствующим» электроном. Используя уравнение Бете-Салпетера в парном приближении, исследуется магнон, как связанное состояние электронов. Вращение спина электронов вводится с помощью преобразованияE 2 симметрии для магнонов и квазиэлектронов, которое отличается от вращения. Обсуждается простой вывод теоремы для низких энергий.
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Shah, M.N., Vitiello, G. Self-consistent formulation of itinerant-electron ferromagnet. Nuov Cim B 30, 21–42 (1975). https://doi.org/10.1007/BF02721491
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DOI: https://doi.org/10.1007/BF02721491