scholarly journals Two-Magnon Bound States in the Heisenberg Ferromagnet with Anisotropic Exchange and Uniaxial Anisotropy Energies

1970 ◽  
Vol 46 ◽  
pp. 61-83 ◽  
Author(s):  
Takashi Tonegawa
Keyword(s):  
Bound States ◽  
Uniaxial Anisotropy ◽  
Heisenberg Ferromagnet ◽  
Anisotropic Exchange

Single-ion magnon bound states in an antiferromagnet with strong uniaxial anisotropy

2000 ◽  
Vol 61 (17) ◽  
pp. 11632-11636 ◽  
Author(s):  
K. Katsumata ◽  
H. Yamaguchi ◽  
M. Hagiwara ◽  
M. Tokunaga ◽  
H.-J. Mikeska ◽  
...  
Keyword(s):  
Bound States ◽  
Uniaxial Anisotropy

Effect of Biquadratic Exchange Upon Ferromagnetic Two-Magnon Bound States. II. Anisotropic Exchange

1974 ◽  
Vol 52 (1) ◽  
pp. 33-39 ◽  
Author(s):  
D. A. Pink ◽  
R. Ballard
Keyword(s):  
Bound States ◽  
Exchange Interactions ◽  
Bound State ◽  
Exchange Term ◽  
Zero Temperature ◽  
Biquadratic Exchange ◽  
Anisotropic Exchange ◽  
Bound State Spectrum ◽  
Mode Pair ◽  
Isotropic Exchange

We have investigated the two-magnon bound state spectrum of a ferromagnetically ordered system for which the Hamiltonian contains an anisotropic bilinear exchange term, an anisotropic biquadratic exchange term, and a single-ion anisotropy term. The bound states, labelled by a wave vector q which we have taken to be in the [111] direction, were calculated by using zero-temperature Green functions. The principal results are: (i) the existence of single-ion bound states in the absence of single-ion anisotropy and conversely, their absence in the presence of such anisotropy, in contrast to the case in which the exchange interactions are isotropic; (ii) the appearance of an S mode for values of q, [Formula: see text]; (iii) the ordering of bound states for isotropic exchange interactions wherein the S0 mode lies below the S1-mode, D-mode pair and where the S1 mode lies below (above) the D mode if they lie below (above) the band, no longer holds.

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