Magnon energy

Fig. 10. Applied field dependence of the = 0 magnon energy gap in Tb—10%Ho demonstrating the validity of the frozen-lattice strain approximation as manifested by the minimum, but non-vanishing, of the gap energy at a held corresponding to the basal plane anisotropy held. Data taken with the field along the hard basal plane direction, except for the curves marked easy (axis) which show a linear increase of gap energy with field. The lines are theoretical curves. Different symbols are used to distinguish data taken at different temperatures. (After Nielsen et al. 1970b.)...

In contrast to the magnetostriction mechanism the spin-orbit coupling is insensitive to the temperature. Experimentally Ai was observed to disappear very rapidly with raised temperature. At the same time the magnon energy diminished so that the A2 gap appeared at the crossing point of MO and TA modes, but with no appreciable reduction in size. Thus, the mixing of MO-TA and MA-TO modes confirms the importance of spin-orbit coupling in the conduction band states of heavy lanthanides. 

The low energy excitation is observed at finite frequencies only for T In moderate magnetic fields its frequency is increasing as shown in Fig. 2d). Such a shift of the low temperature mode and the order parameter-like dependence on temperature has been taken as evidence that the mode cannot be related to a singlet state and must be identified as a longitudinal magnon [33, 34],... 

Not any feature was observed in the single-magnon dispersion that would correlate with the lower-energy two-magnon peak in the inelastic neutron scattering measurements of the stripe-ordered nickelate Lai.69Sr0.3iNiC>4 also.311... 

Magnon - A quantum of magnetic energy associated with a spin wave in a ferromagnetic or antiferromagnetic crystal. 

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