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.
Direct evidence for negative grain boundary potential in Ca-doped and undoped YBa2Cu3O7-x / Schofield, Ma; Beleggia, M; Zhu, Ym; Guth, K; Jooss, C. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 92:19(2004). [10.1103/PhysRevLett.92.195502]
Direct evidence for negative grain boundary potential in Ca-doped and undoped YBa2Cu3O7-x
Beleggia M;
2004
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.
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