Abstract of Publication No. 331
The splitting due to dipolar interactions was investigated for the hexagonal
[1 1 0] direction (y-direction). The Sx and
Sy fluctuations were exclusively visible in the
non-spin-flip and the spin-flip channels, respectively. The splitting creates
minima in the dispersion curves away from the commensurate K-point (1/3 1/3 0).
In CsFeCl3, which does not exhibit
long-range order, the excitations are temperature independent at low
temperature. In RbFeCl3 a soft mode behaviour is observed and the new
minima in the dispersion curves correspond to the observed incommensurate
structures. In the commensurate phase of RbFeCl3 below 1.95 K an
acoustic and an optic mode were observed.