Suppression of surface barriers for flux penetration in Bi 2 Sr 2 CaCu 2 O 8 + δ whiskers by electron and heavy ion irradiation
Suppression of surface barriers for flux penetration in Bi 2 Sr 2 CaCu 2 O 8 + δ whiskers by electron and heavy ion irradiation
复制标题
通过电子和重离子辐照抑制 Bi 2 Sr 2 CaCu 2 O 8 + δ 晶须中助焊剂渗透的表面势垒
DOI：
10.1103/physrevb.64.134517
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发表时间：
2001
影响因子：
3.7
通讯作者：
M. Konczykowski
中科院分区：
文献类型：
--
作者：
J. K. Gregory;M. S. James;S. Bending;C. J. Beek;M. Konczykowski
我们使用微米尺寸的线性霍尔探针阵列研究了辐照对单个超导${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$晶须磁通穿透表面势垒的影响。用2.5 MeV电子或9GeV重离子对样品进行辐照。在5K到高于超导转变温度的温度范围内，在高达1T的磁场中，研究了样品的磁化强度。在所有温度下，高能电子或快重离子的辐照都大大降低了穿透场。在低温下，我们将这归因于对二维“煎饼”涡的Bean-Livingston(BL)表面势垒的抑制，我们的结果与最近的理论预测是合理一致的。在高温下，我们试探性地提出，由于磁通线的BL表面势垒的抑制，使得{H}_p}(T)$的减少。虽然电子辐照大大降低了高温下的磁不可逆性，但在重离子辐照后测量的中等磁滞表明，这为柱状缺陷上的磁通线创造了额外的体钉扎。
We have used micron-sized linear Hall probe arrays to investigate the effects of irradiation on surface barriers for flux penetration in individual superconducting ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ whiskers. Samples were irradiated with 2.5-MeV electrons or 9-GeV heavy (Pb) ions. The magnetization was investigated in the temperature range between 5 K to above the superconducting transition temperature, in magnetic fields up to 1 T. At all temperatures, irradiation by high-energy electrons or swift heavy ions reduces the penetration field substantially. At low temperatures $(Tl50\mathrm{K})$ we attribute this to the suppression of a Bean-Livingston (BL) surface barrier for two-dimensional ``pancake'' vortices, and our results are in reasonable agreement with recent theoretical predictions. At high temperatures $(Tg50\mathrm{K})$ we tentatively propose that the reduction in ${H}_{p}(T)$ is due to suppression of a BL surface barrier for flux lines. While electron irradiation strongly reduces magnetic irreversibility at high temperatures, the moderate hysteresis measured after heavy ion radiation suggests that this creates additional bulk pinning for flux lines on columnar defects.