Temperature dependence of the local structure in superconducting and non-superconducting Tl2Ba2CuOy studied by extended x-ray absorption fine structure
1993; Elsevier BV; Volume: 213; Issue: 3-4 Linguagem: Inglês
10.1016/0921-4534(93)90455-y
ISSN1873-2143
AutoresHiroshi Yamaguchi, Satoru Nakajima, Yuji Kuwahara, H. Ōyanagi, Yasuhiko Syono,
Tópico(s)Superconductivity in MgB2 and Alloys
ResumoAbstract The local structure of Tl 2 Ba 2 CuO y (Tl2201) has been investigated by extended X-ray absorption fine structure (EXAFS) on the Cu K-edge. The result for the high- T c sample with T c =70 K indicates a splitting of Cu-O bondlengths in the CuO 2 plane, which shows a strong temperature dependence over a wide temperature range well above T c , although the crystallographical symmetry of the unit cell is tetragonal. The splitting is evaluated from the filtered EXAFS by the beat-node method, and the maximum splitting distance is ≁0.16 A. The magnitude of the splitting abruptly decreases in the vicinity of T c by more than 10%. On the other hand, no splitting in the in-plane Cu-O bondlengths was observed in non-superconductor samples from room temperature down to 30 K. No apparent change of axial oxygen sites was observed. These facts strongly demonstrate that the local structural distortion in the CuO 2 plane may directly relate to the superconductivity.
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