QUASI-ONE-DIMENSIONAL MAGNETIC-PROPERTIES OF THE (IN SC LU Y)2CU2O5 OXIDES

The intrachain and interchain magnetic interactions in the (In;Sc;Lu;Y)2Cu2O5 ternary oxides have been estimated on the basis of the Heisenberg chain model for S = 1/2, taking into account only the high-temperature experimental data of the magnetic susceptibility. We have also calculated the first three coefficients in the high-temperature expansion series of the magnetic susceptibility for the three-dimensional model of weakly coupled Heisenberg chains. The temperature dependence of the magnetic susceptibility has been compared with the predictions of the models mentioned above. The theoretical values of T(N), obtained by numerical calculations of the Oguchi expression, are in good agreement with experiment. The applied model of the ferromagnetic chains being mutually weakly coupled antiferromagnetically turns out to be a good approximation for the real magnetic system existing in the (In;Sc;Lu;Y)2Cu2O5 oxides.