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

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) approximate to (-0.150,0.422, (1)/(2)) and k'(Br) approximate to (-0.172,0.356, (1)/(2)) and stable below T-N = 18 K for X= Cl and T-N = 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 four 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)mu(B), is significantly less than for X= Cl, 0.88 (1)mu(B) at 2 K. The magnetic structure of the chloride associated with the wave vector k' differs ;from that determined previously for the wave vector k approximate to (0.150,0.422, (1)/(2))

Published in:
Physical Review B, 73, 6, 064422
ETH, Neutron Scattering Lab, CH-5232 Villigen, Switzerland. PSI, CH-5232 Villigen, Switzerland. Univ Warwick, Dept Phys, Coventry CV4 7AL, W Midlands, England. Inst Max Von Laue Paul Langevin, F-38042 Grenoble, France. Rutherford Appleton Lab, ISIS Facil, Didcot OX10 0QX, Oxon, England. Paul Scherrer Inst, CH-5232 Villigen, Switzerland. Univ Zagreb, Inst Phys, HR-10000 Zagreb, Croatia. Ecole Polytech Fed Lausanne, Inst Phys Matiere Complexe, CH-1015 Lausanne, Switzerland. Zaharko, O, ETH, Neutron Scattering Lab, CH-5232 Villigen, Switzerland.
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 Record created 2007-01-24, last modified 2018-03-17

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