Magnetic Raman scattering of the ordered tetrahedral spin- clusters in () compounds

J. Jensen; P. Lemmens; C. Gros

doi:10.1209/epl/i2003-00281-7

All issues

Volume 64 / No 5 (December 2003)

Europhys. Lett., 64 5 (2003) 689-695

Abstract

Issue		Europhys. Lett. Volume 64, Number 5, December 2003


Page(s)		689 - 695
Section		Condensed matter: electronic structure, electrical, magnetic, and optical properties
DOI		https://doi.org/10.1209/epl/i2003-00281-7
Published online		01 November 2003

Europhys. Lett., 64 (5), pp. 689-695 (2003)

Magnetic Raman scattering of the ordered tetrahedral spin- $\frac{1}{2}$ clusters in $\chem{Cu_2Te_2O_5}$ ( $\chem{Br}$ ${_{1-x}}$ $\chem{Cl}$ ${_x}$ ) ${_2}$ compounds

J. Jensen¹, P. Lemmens² and C. Gros³

¹ Ørsted Laboratory, Niels Bohr Institute - Universitetsparken 5 DK-2100 Copenhagen, Denmark
² Max Planck Institute for Solid State Research - D-70569 Stuttgart, Germany
³ Fakultät 7, Theoretische Physik, Universität des Saarlands D-66041 Saarbrücken, Germany

Received: 1 April 2003
Accepted: 17 September 2003

Abstract

Raman light-scattering experiments in the antiferromagnetic phase of the $\chem{Cu_2Te_2O_5}$ ( $\chem{Br}$ $_{1-x}$ $\chem{Cl}$ _x)₂ compounds are analyzed in terms of a dimerized spin model for the tetrahedral $\chem{Cu}$ -clusters. It is shown that the longitudinal magnetic excitation in the pure $\chem{Br}$ system hybridizes with a localized singlet excitation due to the presence of a Dzyaloshinskii-Moriya anisotropy term. The drastic change of the magnetic scattering intensities observed when a proportion of $\chem{Br}$ is replaced by $\chem{Cl}$ ions, is proposed to be caused by a change of the magnetic order parameter. Instead of being parallel/antiparallel with each other, the spins in the two pairs of spin- $\frac{1}{2}$ order perpendicular to each other, when the composition x is larger than about 0.25.

PACS: 75.10.-b – General theory and models of magnetic ordering / 75.30.-m – Intrinsic properties of magnetically ordered materials / 78.30.-j – Infrared and Raman spectra

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