Incommensurate magnetic ordering in Cu2Te2O5X2 (X=Cl, Br) studied by single crystal neutron diffraction

Abstract

Polarized and unpolarized neutron diffraction studies have been carried out on single crystals of the coupled spin tetrahedra systems Cu2Te2O5X2 (X=Cl, Br). A model of the magnetic structure associated with the propagation vectors k'Cl ~ -0.150,0.422,1/2 and k'Br ~ -0.172,0.356,1/2 and stable below TN=18 K for X=Cl and TN=11 K for X=Br is proposed. A feature of the model, common to both the bromide and chloride, is a canted coplanar motif for the 4 Cu2+ spins on each tetrahedron which rotates on a helix from cell to cell following the propagation vector. The Cu2+magnetic moment determined for X=Br, 0.395(5)muB, is significantly less than for X=Cl, 0.88(1)muB at 2K. The magnetic structure of the chloride associated with the wave-vector k' differs from that determined previously for the wave vector k~0.150,0.422,1/2 [O. Zaharko et.al. Phys. Rev. Lett. 93, 217206 (2004)].

References in corpus (10)

• Evidence for an unconventional magnetic instability in the spin-tetrahedra system Cu_2Te_2O_5Br_2
• Longitudinal magnon in the tetrahedral spin system Cu2Te2O5Br2 near quantum criticality
• Magnetism of a tetrahedral cluster spin-chain
• Halogen-mediated exchange in the coupled-tetrahedra quantum spin systems Cu2Te2O5X2 (X=Br,Cl)
• Incommensurate magnetic ordering in $C{u}_{2}T{e}_2{O}_5{X}_2$ (X=Cl,Br) studied by neutron diffraction
• Magnetic Raman scattering of the ordered tetrahedral spin-1/2 clusters in Cu_2Te_2O_5(Br_(1-x)Cl_x)_2 compounds
• Weak antiferromagnetism and dimer order in quantum systems of coupled tetrahedra
• Ground state order and spin-lattice coupling in tetrahedral spin systems Cu2Te2O5X2
• Neutron inelastic scattering investigation of the magnetic excitations in Cu_2Te_2O_5X_2 (X=Br, Cl)
• Anisotropic field dependence of the magnetic transition in Cu2Te2O5Br2

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