Since the discovery of copper telluride Cu2Te2O5X2 systems (where X = Cl or Br) [1] their magnetic properties have been subject of certain experimental and theoretical studies. Magnetic moments (S = ½ ; ; ; ) are located on Cu2+ ions in tetrahedral clusters. This geometry together with an antiferomagnetic interaction between Cu2+ ions may lead to a magnetic frustration. While some authors report about the frustration in these magnetic systems [2], others successfully describe their magnetic properties without considering frustration [1]. However, no systematic research of magnetic properties that are characteristic for frustrated systems, e.g. a difference between zero-field and field-cooled susceptibility, frequency- dependent cusp in the ac susceptibility and slow time-decay of a thermoremanent magnetization below the freezing temperature, have been made. The aim of this study is to search for frustration-like magnetic properties in these systems. This can lead to unique description of the magnetism in copper telluride Cu2Te2O5X2 systems. Single crystals of Cu2Te2O5Br2-xClx (x = 0, 0.5, 1, and 2) were grown by a halogen vapor transport technique. Magnetization measurements were made by a Quantum Design MPMS-XL-5 SQUID susceptometer. The susceptibility h(T) was measured between 300 K and 2 K. For all six samples the h(T) increases with decreasing temperature form 300 K to about 25 K. At that temperature the susceptibility reaches maximum. The temperature of the susceptibility maximum is only slightly altered from sample to sample. From 25 K down to 2 K susceptibility decreases and reaches a plateau below 2 K. No splitting between zero-field and field cooled susceptibility measured in H = 1 Oe have been detected. The ac susceptibility was measured at 1 Hz, 10 Hz, 100 Hz and 1000 Hz. The temperature of the maximum of ac susceptibility does not shift with the frequency of the applied magnetic field. The thermoremanent magnetization was measured after cooling the samples from 100 K to 12 K in a magnetic field of 8 Oe. No sign of thermoremanent magnetization was detected after the magnetic field was cut to zero. These results indicate that frustration is not present in copper telluride Cu2Te2O5X2 systems, at least to the extent as observed in canonical spin glasses and geometrically frustrated antiferomagnets. [1] M. Johnsson, K.W.Tornroos, F.Mila, P.Millet, Chem. Mater. 12, 2853 (2000). [2] O.Zaharko A.Daoud-Aladine. S.Streule, J.Mesot, P.J.Brown, M.Berger, Phys. Rev. Lett. 93, 217206 (2004).

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