Details

Autor(en) / Beteiligte

• Giebultowicz, T. M.
• Fernandez-Baca, J. A.
• Nicklow, R. M.
• Furdyna, J. K.
• Debska, U.

Titel

Spin dynamics in a diluted Heisenberg NN antiferromagnet on a HCP lattice: Zn1− x Mn x Se (abstract)

Ist Teil von

• Journal of applied physics, 1993-05, Vol.73 (10), p.5660-5660

Erscheinungsjahr

1993

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The nature of magnetic excitations in disordered and short-range ordered antiferromagnetic systems continues to be an interesting problem. The family of AII1−xMnxBVI alloys (AII=Zn, Cd, Hg, BVI=S, Se, Te) offers highly interesting prototypes for such studies. In these systems, which crystallize in the zinc blende (ZB) or wurtzite structure, the Mn ions form, respectively, diluted FCC or HCP Heisenberg spin lattices with dominating nearest-neighbor AF coupling. Due to the strong frustration inherent in such lattices these systems do not exhibit long-range spin order even for Mn concentrations as high as x=0.70. Neutron scattering studies of spin dynamics in the zinc-blende forms (Zn1−xMnxTe and Cd1−xMnxTe) have been reported in a recent article.1 In the present paper we report the results of experiments on a wurtzite-type system, Zn1−xMnxSe, with x=0.55 and 0.40. As in the previous case of ZB alloys, the data reveal the existence of magnon-like modes that are extremely strongly damped, but still show a pronounced dispersive behavior. The range of static AF spin–spin correlations in Zn1−xMnxSe is extremely short (ξ=κ−1=5–15 Å), and exhibits a significant anisotropy. The energy of the observed excitation is clearly correlated with ξ, i.e., it is higher in the Q-space directions for which the correlation range is longer. The results are discussed in the context of the existing theoretical models.