Direct evidence for negative grain boundary potential in Ca-doped and undoped YBa2Cu3O7-x.

Abstract

Using electron holography in a transmission electron microscope, we obtained direct evidence for the reduction of negative charge at grain boundary dislocations in Ca-doped YBa2Cu3O7 (YBCO) when compared to undoped YBCO. Because of the finite width of the valence band in the superconducting CuO2 planes, the negative grain boundary charge can lead to a depletion of electron holes available for superconductivity. A significant reduction in the size of the perturbed region in the Ca-doped samples appears to be the principal mechanism for the improved interfacial superconductivity.

• Authors: Marvin A Schofield, Marco Beleggia, Yimei Zhu, Karsten Guth, Christian Jooss
• Journal: Physical review letters (Phys Rev Lett) Vol. 92 Issue 19 Pg. 195502 (May 14 2004) ISSN: 0031-9007 [Print] United States
• PMID: 15169414 (Publication Type: Journal Article)