SrTiO_3基片上Tl-2212双晶约瑟夫森结的动态特性及噪声影响研究

Dynamic characteristics of Tl-2212 bicrystal Josephson junctions on SrTiO_3 substrates and the effect of noise on it

在SrTiO3(STO)基片上制作了Tl-2212双晶约瑟夫森结,并对其进行了微波辐照下的I-V特性测试,观察到了夏皮罗台阶,符合约瑟夫森电压-频率关系.利用数值仿真对约瑟夫森结建立了RCSJ模型,仿真结果与实验数据符合较好,利用此模型深入研究了噪声对结动态特性的影响,解释了噪声影响下结的微波感应台阶幅度减小和极小值展宽现象,提出了有效噪声温度为工作温度和外部噪声的等效温度之和.

Tl-2212 bicrystal Josephson junctions on SrTiO_3 substrates have been fabricated.The I-V characteristic of a Josephson junction under microwave radiation were measured,and microwave induced steps were observed in accordance with the Josephson frequency-voltage relationship.The RCSJ model including noise of bicrystal Josephson junction was constructed through numerical simulation,and the results of simulation were in good agreement with the experimental data.Using the RCSJ model,we investigated the effect of noise on the dynamic characteristics of Josephson junction through simulation, and explained the phenomenon of reduced height and increased breadth of the minima of microwave induced steps. We proposed that the effective noise temperature should be the sum of operational temperature and equivalent temperature of the external noise.