PARAMAGNETIC PROPERTIES OF THE SR OVERDOPED (LA,SR)(2)CUO4 SYSTEM

The magnetic behavior of the non-superconducting Sr overdoped La2-xSrx CuO4 x > 0.25 system was studied by Mossbauer spectroscopy (MS) and ES R studies on 0.3% Fe-57 doped materials. Both experimental techniques indicate clearly that in the metallic state, the CuO2 planes are param agnetic. The MS spectra are a superposition of two sub-spectra corresp onding to inequivalent Fe sites. At 4.1 K, the complicated spectra are interpreted as due to local paramagnetic fluctuations of dilute Fe, w ith slow relaxation rates. The ESR spectra are composed of two lines. The centroid of the most intense resonance line is independent of temp erature and corresponds to well isolated paramagnetic Fe ions. Thus co mpetition between SC and AFM exists only in the region of low x.