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.
In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed...In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed laser deposition.Our result shows that the termination of SrTiO3 has only a negligible effect on the properties of YBCO. In contrast, we found that capping a non-superconducting oxide layer can generally enhance the superconductivity of YBCO. PrBa2 Cu3 O7,La2 CuO4, LaMnO3, SrTiO3, and LaAlO3 have been examined as capping layers, and the minimum thickness of superconducting YBCO with capping is ~ 2 unit cells–3 unit cells. This result might be useful in constructing good-performance YBCO-based field effect devices.展开更多
The dependence of the effective penetration depthλe,on the external magnetic field in a high-Tc superconducter YBa2Cu3O7 has been measured by both dc and ac methods at liquid-nigtrogen temperature.It is found,thatλe...The dependence of the effective penetration depthλe,on the external magnetic field in a high-Tc superconducter YBa2Cu3O7 has been measured by both dc and ac methods at liquid-nigtrogen temperature.It is found,thatλe increases rapidly with increasing external field and is 0.13~0.15mm in macroscopic scale.The Hcl of the specimen,about 800e at 77K here,can be determined more reliably by comparing dcλe with acλe.The difference betweenλedc andλeac,and the jumping ofλedc may indicate the characters of superconducting glass.展开更多
We fabricated YBa2Cu3O7–d bulk ceramics with a domestic microwave oven and investigated the effect of pressure at the press procedure. If the pressure was not high enough, the ratio of BaCuO2 phase became large, esti...We fabricated YBa2Cu3O7–d bulk ceramics with a domestic microwave oven and investigated the effect of pressure at the press procedure. If the pressure was not high enough, the ratio of BaCuO2 phase became large, estimated from x-ray diffraction (XRD) measurements. We found that the pressure should be 700 kgf/cm2 at least in order to suppress the BaCuO2 phase.展开更多
YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by X-ray wide angle diffraction,reflection,diffuse scattering and topography.Theresults show tha...YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by X-ray wide angle diffraction,reflection,diffuse scattering and topography.Theresults show that for the yttria stabilized ZrO2(YSZ) substrate,the presence of an ECO buffer layer improves the crystalline quality of the YBCO film,while a negative effect is observed for the SrTiO3(STO) substrate.The lateral correlation length for a sample grown on a YSZ substrate with ECO buffer Layer is much greater than grown on an STO subetrate.The STO substrate used has mosaic structure.2001 Elsevier Science B.V.All rights reserved.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 Key Research and Development Program of the Ministry of Science and Technology of China(Grants Nos.2017YFA0303002and 2016YFA0300204)the Fundamental Research Funds for the Central Universities,China
文摘In this study, we have explored the ways to fabricate and optimize high-quality ultrathin YBa2 Cu3 O7-δ(YBCO) films grown on single-crystal(001) SrTiO3 substrates. Nearly atomic-flat YBCO films are obtained by pulsed laser deposition.Our result shows that the termination of SrTiO3 has only a negligible effect on the properties of YBCO. In contrast, we found that capping a non-superconducting oxide layer can generally enhance the superconductivity of YBCO. PrBa2 Cu3 O7,La2 CuO4, LaMnO3, SrTiO3, and LaAlO3 have been examined as capping layers, and the minimum thickness of superconducting YBCO with capping is ~ 2 unit cells–3 unit cells. This result might be useful in constructing good-performance YBCO-based field effect devices.
基金Project suported by the National Science Fundation of China.
文摘The dependence of the effective penetration depthλe,on the external magnetic field in a high-Tc superconducter YBa2Cu3O7 has been measured by both dc and ac methods at liquid-nigtrogen temperature.It is found,thatλe increases rapidly with increasing external field and is 0.13~0.15mm in macroscopic scale.The Hcl of the specimen,about 800e at 77K here,can be determined more reliably by comparing dcλe with acλe.The difference betweenλedc andλeac,and the jumping ofλedc may indicate the characters of superconducting glass.
文摘We fabricated YBa2Cu3O7–d bulk ceramics with a domestic microwave oven and investigated the effect of pressure at the press procedure. If the pressure was not high enough, the ratio of BaCuO2 phase became large, estimated from x-ray diffraction (XRD) measurements. We found that the pressure should be 700 kgf/cm2 at least in order to suppress the BaCuO2 phase.
文摘YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by X-ray wide angle diffraction,reflection,diffuse scattering and topography.Theresults show that for the yttria stabilized ZrO2(YSZ) substrate,the presence of an ECO buffer layer improves the crystalline quality of the YBCO film,while a negative effect is observed for the SrTiO3(STO) substrate.The lateral correlation length for a sample grown on a YSZ substrate with ECO buffer Layer is much greater than grown on an STO subetrate.The STO substrate used has mosaic structure.2001 Elsevier Science B.V.All rights reserved.
