MAGNETIC FIELD DEPENDENCE OF HIGH Tc SEMICONDUCTING CERAMICS

We report the magnetization M as a function of magnetic field H and temperature T for both semiconducting La2-,SrXCu04-, and Y1Ba2C~306+x.An anomalous magnetic field dependence has been observed for each of these samples.Below TN, the application of high field at small x (< 0.02) for La2-,SrxCuOq-y and for Y1Ba2cu3o6+, at x = 0, there is an anomalous behavior for M (R) , suggestive of a presence of a ferromagnetic component.For Y1Ba.~CusOs+, samples of x = 0.25 and 0.34, there is a sublinear behavior of M on H. Possible models are discussed for these novel phenomena.