Abstracts 1999

Abstract of Publication No. 331

B. Dorner, D. Petitgrand and H. U. Güdel
Minute splitting of magnetic excitations due to dipolar interactions in CsFeCl3 and RbFeCl3 observed with polarised neutrons
Physica B 267-268, 263-265 (1999)      Full Text (PDF)      DOI-Link     

Abstract: 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.

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