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Magnon dispersion relation in europium iron garnet
Author(s) -
Liu N. L. Huang
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560050875
Subject(s) - magnon , anisotropy , europium , isotropy , condensed matter physics , dispersion (optics) , dispersion relation , exchange interaction , ion , physics , sign (mathematics) , order (exchange) , chemistry , quantum mechanics , ferromagnetism , mathematics , finance , economics , mathematical analysis
The acoustic magnon dispersion constant D of EuIG is compared with that of YIG by considering the orbitally anisotropic exchange interaction between Eu and Fe ions. Such interaction effectively couples two Fe ions and hence affects the magnon spectrum of the iron sublattice. It is found that the Eu‐Fe exchange enhances the value of D EuIG over that of D YIG regardless of the sign of the exchange parameters a μν . Furthermore, the isotropic part together with the second and fourth order anisotropic terms in the exchange is found to contribute about 1.2 cm −1 to D EuIG — D YIG , and a small amount of sixth order anisotropy a 60 / a 00 ˜ 4% could contribute to this difference by as much as 5 cm −1 . This suggests that the sixth order anisotropy could be the main source for the difference between D = 33 cm −1 and D YIG = 27 cm −1 obtained by the parallel pumping experiments.