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Dispersion in Ferromagnets Interacting with Phonons
Author(s) -
Suguna A.,
Shrivastava K. N.
Publication year - 1980
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220990131
Subject(s) - magnon , condensed matter physics , phonon , physics , wave vector , dispersion relation , ferromagnetism , coupling constant , dispersion (optics) , scattering , discontinuity (linguistics) , degenerate energy levels , quantum mechanics , mathematics , mathematical analysis
Considering the magnon‐phonon interaction it is found that there is a net reduction of Heisenberg exchange. The reduction is maximum for the magnon wave vector given by K 0 = v /(2 cD ) where v is the sound velocity and D is just 2 SJa 0 2with a 0 as the lattice constant. Thus the reduction is found to depend inversely on the exchange itself. There is also a new analog of Kohn like discontinuity occuring at the magnon wave vector k 8 = ½ ( q m + v / cD ) with q m as the maximum wave vector of the phonons. In consideration of thermal magnon scattering a kink in the magnon dispersion is thus predicted at k s . The approximate temperature dependence arising in the exchange from the magnon‐phonon coupling is discussed.