Double-well potential for oxygen ion vibrations in Nd2-xCe xCuO4-δ

Abstract

X-ray absorption spectra of the oxide systems Nd2-xCe xCuO4-δ (NCCO) above the K-Cu absorption edge were investigated in temperature range 4 300 K. It is assumed that oxygen ions in superconductive CuO2 plane move in a double-well potential similarly to abnormal oxygen vibrations uncovered earlier in superconductive systems Ba1-xKxBiO3 and La2-xSr xCuO4. A model of relationship between electronic and local crystalline structures is proposed. Obtained results point to the direct connection of the observed local dynamic structure nonuniformity with local dynamic charge ordering. Role of dynamic charge ordering in superconductive CuO2 plane in HTSC mechanism is discussed. © 2009 IOP Publishing Ltd.