EPR study of La1.854Sr0.146CuO4

EPR spectra of La1.854Sr0.146CuO4 and its aging effect have been studied. T emperature variation of the EPR spectra of La1.854Sr0.146CuO4 (from room te mperature to liquid nitrogen temperature, LNT) along with CaCuO2 for compar ison has been carried out. In all the materials, after quenching the most a bundant species, the ferromagnetically coupled Cu-tetramer (CuO)(4) was obt ained. The (CuO)(4) square, being the unit cell of all important two-dimens ional CuO2 planes superconductors, may reflect the properties of the superc onductors. At about 100 K, in La1.854Sr0.146CuO4, the tetramer signal was d estabilized, disappeared and was immediately followed by a new signal, whic h may be seen as a signature of formation of quantum stripes. (C) 1999 Else vier Science B.V. All rights reserved.