文档介绍：
二硼化镁薄膜中超导转变温度以上的超导
涨落电导#
王越,张辰,王达,张焱*
5
10
(北京大学物理学院,北京 100871)
摘要:为研究 MgB2 超导体在超导转变温度 Tc 以上的超导涨落,测量了由混合物理化学气
相沉积法制备的 MgB2 薄膜的电阻输运特性。通过拟合薄膜在较高温度区间的电阻,确定了
样品在低温区超导转变附近的正常态电阻,从而确定了样品在 Tc 以上的超导涨落电导。结
果表明,在接近于 Tc 时,MgB2 薄膜的超导涨落展现出三维超导涨落的特征;在远离 Tc 时,
涨落电导快速减小,偏离传统的理论预言。分析表明,这一现象可以通过在超导涨落谱中引
入一个能量截止而得到比较合理的解释。
关键词:凝聚态物理;二硼化镁薄膜;超导涨落
中图分类号:O469
15
Fluctuation-induced conductivity above Tc in MgB2 thin
film
WANG Yue, ZHANG Chen, WANG Da, ZHANG Yan
(School of Physics, Peking University, Beijing 100871)
20
25
30
35
40
Abstract: To investigate the superconducting fluctuations in MgB2 above the superconducting
transition temperature Tc, the resistive transport has been measured in a MgB2 thin film which
was grown by the hybrid physical-chemical vapor deposition method. The fluctuation-induced
conductivity is determined by subtracting the normal-state resistivity which has been estimated by
fitting the resistivity at high temperature and extrapolating it down to the superconducting
transition regime. It shows that very near Tc the fluctuation conductivity in MgB2 follows the
traditional theory for superconducting fluctuations in three-dimensional superconductors. At
higher temperatures, however, a rapid falloff of the fluctuation conductivity deviating from the
theoretical predication has been observed. It is suggested that this phenomenon could be explai