It is suggested that the extremely large oxygen isotopic Tc shift recently reported in YBa2Cu3O7 may not be an intrinsic mass effect related to the mechanism but due to the small difference of the oxygen contents.
I. INTRODUCTION Since the discovery of superconductivity above 40 K in the La-Ba-Cu-O system andabove 90 K in Y-Ba-Cu-O oxides, tremendous effort has been made to study the properties of high-T_c superconducting thin ...I. INTRODUCTION Since the discovery of superconductivity above 40 K in the La-Ba-Cu-O system andabove 90 K in Y-Ba-Cu-O oxides, tremendous effort has been made to study the properties of high-T_c superconducting thin films. For the preparation of superconducting films two main techniques, the e-beam evaporation and sputtering, have been used. The processes展开更多
It is verified that the phonon scattering process and the residual linewidthare the dominant factors of the linewidth of 2210 cm^(-1) IR absorption peak except the anomalous linewidth at 200 K. By investigating the an...It is verified that the phonon scattering process and the residual linewidthare the dominant factors of the linewidth of 2210 cm^(-1) IR absorption peak except the anomalous linewidth at 200 K. By investigating the anomalities of the peak shape and thelinewidth of the peak at 200 K, we put forward a mechanism that the T_d symmetry of defect-complex corresponding to the 2210 cm^(-1) peak can he transferred into the D_(2d) symmetry as temperature rises to above 200 K. The quantitative analysis shows that the V+4H-model is indeed of two states: The T_d configuration is stable at temperature lower than 200 K, while the D_(2d) one is stable at temperature higher than 200 K. We can draw the conclusion that the V +4H-model corresponds to the 2210 cm^(-1) IR absorption peak from the symmetric breaking mechanism, which can quantitatively fit the experimental results.展开更多
基金This work was supported by National Science Fund of China.
文摘It is suggested that the extremely large oxygen isotopic Tc shift recently reported in YBa2Cu3O7 may not be an intrinsic mass effect related to the mechanism but due to the small difference of the oxygen contents.
基金Project supported by the National Center for Research and Development on Superconductivity and the Sci ence Foundation of Academia Sinica
文摘I. INTRODUCTION Since the discovery of superconductivity above 40 K in the La-Ba-Cu-O system andabove 90 K in Y-Ba-Cu-O oxides, tremendous effort has been made to study the properties of high-T_c superconducting thin films. For the preparation of superconducting films two main techniques, the e-beam evaporation and sputtering, have been used. The processes
文摘It is verified that the phonon scattering process and the residual linewidthare the dominant factors of the linewidth of 2210 cm^(-1) IR absorption peak except the anomalous linewidth at 200 K. By investigating the anomalities of the peak shape and thelinewidth of the peak at 200 K, we put forward a mechanism that the T_d symmetry of defect-complex corresponding to the 2210 cm^(-1) peak can he transferred into the D_(2d) symmetry as temperature rises to above 200 K. The quantitative analysis shows that the V+4H-model is indeed of two states: The T_d configuration is stable at temperature lower than 200 K, while the D_(2d) one is stable at temperature higher than 200 K. We can draw the conclusion that the V +4H-model corresponds to the 2210 cm^(-1) IR absorption peak from the symmetric breaking mechanism, which can quantitatively fit the experimental results.
