Critical currents near 106 A cm-2 at 77 K in neutron-irradiated single-crystal YBa2Cu3O7
Critical currents near 106 A cm-2 at 77 K in neutron-irradiated single-crystal YBa2Cu3O7
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DOI：
10.1038/342055a0
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发表时间：
1989-11
期刊：
影响因子：
64.8
通讯作者：
R. B. Dover;E. Gyorgy;L. Schneemeyer;J. Mitchell;K. V. Rao;R. Puźniak;J. Waszczak
中科院分区：
文献类型：
--
作者：
R. B. Dover;E. Gyorgy;L. Schneemeyer;J. Mitchell;K. V. Rao;R. Puźniak;J. Waszczak
在YBa_2Cu_3O_7中的缺陷被证明是弱磁通钉扎点，导致在中等磁场中在转变温度Tc附近的可逆磁化1、磁化衰减2和非零磁化率3。这些影响限制了生长态材料3的技术效用。这并不完全令人惊讶，因为单晶和多晶材料都是在预期使缺陷密度最小化的条件下生长的，但是这些材料中的弱钉扎仍然提出了对临界电流密度的可能的固有限制的问题。本文报道了用快中子辐照引入缺陷的YBa_2Cu_3 O_7单晶，在77 K和9 kOe下，获得了临界电流密度J_c = 1.6 × 105 A·cm ~（-2）。(In辐照和未辐照的晶体，通过测量由感应持续电流产生的磁矩来推断临界电流密度。这一百倍增强的Jc相对于未经辐照的晶体表明，人工诱导的缺陷可以作为强磁通钉扎网站，和缺陷的分析应增加我们的理解磁通钉扎在高Tc超导体。
THE defects in as-grown bulk YBa2Cu3O7have been shown to act as weak flux pinning sites, leading to a reversible magnetization1, magnetization decay2and non-zero resistivity3in moderate magnetic fields at temperatures near the transition temperature,Tc. These effects limit the technological utility of the as-grown material3. This is not entirely surprising, as both single crystals and polycrystalline materials are grown under conditions expected to minimize the defect density, but the weak pinning in these materials has nevertheless raised the issue of a possible intrinsic limitation to the critical current density. Here we report the attainment of a critical current density,Jc, of ∼ 6 x 105A cm-2at 77 K and 9 kOe, in a single crystal of Yba2Cu3O7irradiated with fast neutrons to introduce defects. (In both irradiated and unirradi-ated crystals, the critical current density was inferred by measuring the magnetic moment resulting from an induced persistent current.) This hundredfold enhancement ofJcrelative to unirradiated crystals demonstrates that artificially induced defects can act as strong flux pinning sites, and analysis of the defects should increase our understanding of flux pinning in high-Tcsuperconductors.