TRANSPORT AND MAGNETIC PROPERTIES OF Gd3-xOxS4

Magnetic and Transport Properties of Gd~ D S. were measured. Magnetic properties are understood by a homogeneous d-f exchange model with a small Fermi energy treated before by us . Xransport properties are not understood by a usual separated bound magnetic polaron model . Magnetic Wigner localization is proposed Gd-, P S. is a interesting material in the 3-x x 4 3 sense that the vacancies in Gd sites enter, randomly even at T =0 in the concentration range 0 is evaluated as functions of and the applied field H e xt • Fig. 1 Magnetization vs external field for low and high temperature. As seen in figure 2a as an example, J f€(0) equals J (0) determined from 6 for small , but deviates rapidly with increasing , and finally becomes negative . The results are summarized in figure 2b for various external fields . Sharp drops in J„ f f (0) seen in the curves for H e x t = 4 0 and 64k0e,.both of Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1980533