EFFECTS OF ZN SUBSTITUTION FOR CU ATOMS IN LANTHANUM STRONTIUM SUPERCONDUCTORS

Electron paramagnetic resonance (EPR) investigations of the La1-xSrxCu1-yZnyO4 compound have been undertaken in order to determine the nature of high-Tc superconductivity suppression by doping with nonmagnetic ions. The appearance of a new resonance line with Zn doping was observed. Analysis of this signal reveals that Zn substitution induces the creation of localized magnetic moments, which are localized on Cu ions. The string mechanism of this phenomenon, based on the local U(1) gauge symmetry of the electron spin liquid, is outlined. According to this mechanism, near each substituted ion a spinon-holon pair forms, which reveals the properties of the localized magnetic moments. The peculiarities of superconductivity suppression in the presence of these Zn-stimulated complexed are discussed. The experimental results can be used for the verification of various microscopic mechanisms of hihg-Tc superconductivity. © 1990.