Electron energy-loss spectroscopy of Sr2CuO2+δCl2−y: Overdoping and role of apical oxygen for high-Tc superconductivity

✍ Scribed by H. Yang; Q.Q. Liu; F.Y. Li; C.Q. Jin; R.C. Yu

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 421 KB
• Volume: 453
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2007.01.001

✦ Synopsis

By measuring O 1s and Cu 2p 3/2 absorption edges of Sr 2 CuO 2+d Cl 2Ày using orientation-dependent high-energy electron energy-loss spectroscopy, the changes of the unoccupied electronic structure close to the Fermi level induced by stoichiometry variations have been explored. An interesting hole redistribution between the in-plane O 2p orbitals and apical O 2p orbitals induced by the doping level has been revealed in this system. For the low-doped samples in which superconductivity is absent, the holes reside predominantly on the oxygen sites of the CuO 2 plane, while for the high-doped samples in which superconductivity appears, considerable holes are found to enter the apical oxygen sites. This result reveals clearly that the apical O 2p holes play an important role in the occurrence of superconductivity in the 'apical oxygen doped' Sr 2 CuO 2+d Cl 2Ày system.