1999/10/07 by Giniyat Khaliullin, G. Khaliullin, R. Kilian · 3 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Colossal magnetoresistance #Condensed matter physics #Curie temperature #Degenerate energy levels #Ferromagnetism #Magnetic and transport properties of perovskites and related materials #Magnetic field #Magnetoresistance #Magnon #Physics #Quantum mechanics #Rare-earth and actinide compounds #Renormalization #Softening #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.61.3494
arxiv created 1999/10/07 · openalex publication_date 2000/02/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In metallic manganites with low Curie temperatures, a peculiar softening of the magnon spectrum close to the magnetic zone boundary has experimentally been observed. Here we present a theory of the renormalization of the magnetic excitation spectrum in colossal magnetoresistance compounds. The theory is based on the modulation of magnetic exchange bonds by the orbital degree of freedom of double-degenerate eg electrons. The model considered is an orbitally degenerate double-exchange system coupled to Jahn-Teller active phonons which we treat in the limit of strong on-site repulsions. Charge and coupled orbital-lattice fluctuations are identified as the main origin of the unusual softening of the magnetic spectrum.