MEASUREMENTS AND CALCULATION OF MAGNETIC-SUSCEPTIBILITY OF LOW-CONCENTRATED SEMIMAGNETIC SEMICONDUCTOR GDXY2-XO3

The low-concentrated gadolinium-yttrium mixed oxides GdxY2-xO3 (x = 0.02, 0.06, 0.10) were synthesized. Magnetic susceptibility was measured by the Faraday method in a temperature range 4 < T < 270 K and behaviour in accordance with the Curie-Weiss law was obtained. Starting from the exclusive 24d-site occupancy of Gd3+ ions for concentrations x less than or equal to 0.41 and from the short range of superexchange Gd(24d)-O-Gd(24d) interaction, the temperature dependence of the magnetic susceptibility was calculated using the isolated cluster model in the nearest-neighbour approximation. If random distribution of magnetic ions is assumed, good agreement between calculated and experimental chi(-1)(T) data can be found only for the lowest concentration x=0.02. Making use of both geometric and modified distributions, the enhancement of the clusterisation of the magnetic cations for increased concentrations x = 0.06 and 0.10 was found.