6533b821fe1ef96bd127acd8

RESEARCH PRODUCT

Spin Dynamics of the Half-Integer-Spin Quasi-One-Dimensional Heisenberg Antiferromagnet CsMnI3

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Magnetic excitations of CsMnI 3 , a quasi-one-dimensional Heisenberg antiferromagnet with S =5/2, have been measured by means of inelastic neutron scattering. Magnetic excitations in the low temperature phase are in good agreement with the predictions of the conventional linear spin-wave theory. In particular, in accordance with the linear spin-wave theory, we found three separate modes at Q =(0, 0, 1) instead of a threefold degenerate mode as seen in CsNiCl 3 ( S =1). It confirms that the spin dynamics of the integer spin value system are very different from those of the half-integer spin value system, even in their three-dimensionally ordered phase. Magnetic excitations in the intermediate phase have been also studied and it is found that the excitations were similar to those in the low temperature phase, except some overdamped intensities at certain reciprocal points. These intensities can be associated to the slow rotational motions of the spins around the c -axis.