The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The conc...The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The concentration of Y211 nanoinclusions has been systematically varied inside YBCO thin films prepared by laser ablation technique using surface modified target approach.Large pinning force density values(Fp∼0.5 TNm^(−3)at 4.2 K,9 T)have been observed for the YBCO film with moderate concentration of Y211 nanoinclusions(3.6 area%on ablation target).In addition,uniform enhancement in critical current density(J_(c))was observed in the angular dependent J_(c)measurement of YBCO+Y211 nanocomposite films.Y211 nanoinclusions have been found to be very efficient in pinning the quantized vortices thereby enhancing the in‐field J_(c)values over a wide range of temperature.Increasing the concentration of Y211 secondary phase into Y123 film matrix results into agglomeration of Y211 phase and observed as increased Y211 nanoparticle size.These larger secondary phase nanoparticles are not as efficient pinning centers at lower temperatures as they are at higher temperatures due to substantial reduction of the coherence length at lower temperatures.Investigation of the temperature dependence of J_(c)for YBCO+Y211 nanocomposite films has been conducted and possible vortex pinning mechanism in these nanocomposite films has been discussed.展开更多
Iron-based superconductor,a promising candidate for high-field applications,has attracted significant attentions.For practical utilization,the superconducting tapes should have high transport critical current density(...Iron-based superconductor,a promising candidate for high-field applications,has attracted significant attentions.For practical utilization,the superconducting tapes should have high transport critical current density(J_(c)),low production cost,larger mechanical strength and good homogeneity.In this study,seven-filament Cu/Agsheathed(Ba,K)Fe_(2)As_(2)tapes were fabricated from round and square wires.It is found that the tapes rolled from square wires have a desirable uniformity of filament deformation and distribution,compared with the ones rolled from round wires.Moreover,the J_c of tape was obviously improved by using square drawing dies instead of traditional round ones.For the tapes rolled from square wires annealed under ambient and 2 MPa by hot pressing,the transport J_c values reached 1.51×10^(4) A·cm^(-2)and 4.86×10^(4) A.cm^(-2)(4.2K,10T),respectively.The deformation process on the cross section of the tapes during rolling was analyzed by using the powder-flow model.These results indicate a potential application of Cu/Ag(Ba,K)Fe_(2)As_(2)tapes in high-magnetic-field region.展开更多
基金supported by the ALCA project of Japan Science and Technology Agency.
文摘The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The concentration of Y211 nanoinclusions has been systematically varied inside YBCO thin films prepared by laser ablation technique using surface modified target approach.Large pinning force density values(Fp∼0.5 TNm^(−3)at 4.2 K,9 T)have been observed for the YBCO film with moderate concentration of Y211 nanoinclusions(3.6 area%on ablation target).In addition,uniform enhancement in critical current density(J_(c))was observed in the angular dependent J_(c)measurement of YBCO+Y211 nanocomposite films.Y211 nanoinclusions have been found to be very efficient in pinning the quantized vortices thereby enhancing the in‐field J_(c)values over a wide range of temperature.Increasing the concentration of Y211 secondary phase into Y123 film matrix results into agglomeration of Y211 phase and observed as increased Y211 nanoparticle size.These larger secondary phase nanoparticles are not as efficient pinning centers at lower temperatures as they are at higher temperatures due to substantial reduction of the coherence length at lower temperatures.Investigation of the temperature dependence of J_(c)for YBCO+Y211 nanocomposite films has been conducted and possible vortex pinning mechanism in these nanocomposite films has been discussed.
基金supported by the National Key R&D Program of China (2018YFA0704200 and 2017YFE0129500)the National Natural Science Foundation of China (51861135311, U1832213 and 51721005)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences (XDB25000000)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences (QYZDJ-SSWJSC026)
基金financially supported by the National Natural Science Foundation of China(Nos.U1832213,51721005 and 51861135311)the National Key R&D Program of China(Nos.2018YFA0704200 and 2017YFE0129500)+1 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(No.QYZDJ-SSW-JSC026)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB25000000)。
文摘Iron-based superconductor,a promising candidate for high-field applications,has attracted significant attentions.For practical utilization,the superconducting tapes should have high transport critical current density(J_(c)),low production cost,larger mechanical strength and good homogeneity.In this study,seven-filament Cu/Agsheathed(Ba,K)Fe_(2)As_(2)tapes were fabricated from round and square wires.It is found that the tapes rolled from square wires have a desirable uniformity of filament deformation and distribution,compared with the ones rolled from round wires.Moreover,the J_c of tape was obviously improved by using square drawing dies instead of traditional round ones.For the tapes rolled from square wires annealed under ambient and 2 MPa by hot pressing,the transport J_c values reached 1.51×10^(4) A·cm^(-2)and 4.86×10^(4) A.cm^(-2)(4.2K,10T),respectively.The deformation process on the cross section of the tapes during rolling was analyzed by using the powder-flow model.These results indicate a potential application of Cu/Ag(Ba,K)Fe_(2)As_(2)tapes in high-magnetic-field region.
