摘要
Resistive transitions of the new superconductor MgB_(2) are carried out under magnetic fields from 0 to 8 T.It is found that the irreversibility field Hirr(T)and the upper critical field Hc2(T)obtained are very close to those determined in the magnetic measurement.By using the Arrhenius activation lawρ=ρ0exp(-U/kBT),the activation barrier U has been determined by the low dissipation part of R(T)curves.It is found that U■kBT manifests a very weak thermal activation and thermal fluctuation effect.This may further indicate that the flux dynamics near Hirr(T)is induced by strong quantum fluctuation and tunneling of vortices.
作者
金灏
闻海虎
李世亮
赵志文
倪泳明
任治安
车广灿
杨海鹏
刘智勇
郑东宁
赵忠贤
JIN Hao;WEN Hai-Hu;LI Shi-Liang;ZHAO Zhi-Wen;NI Yong-Ming;REN Zhi-An;CHE Guang-Can;YANG Hai-Peng;LIU Zhi-Yong;ZHENG Dong-Ning;ZHAO Zhong-Xian(National Laboratory for Superconductivity,Institute of Physics and Center for Condensed Matter Physics,Chinese Academy of Sciences,Beijing 100080)
基金
Supported by the Ministry of Science and Technology of China(NKBRSF-G19990646)
the National Natural Science Foundation of China under Grant No.19825111.