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arXiv 1006.2184cond-mat.supr-concond-mat.mes-hallcond-mat.str-elquant-ph
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Shapiro台阶对多能隙超导约瑟夫森结中$\pm s$波对称性的直接探测

Shapiro Steps as a Direct Probe of $\pm s$-wave Symmetry in Multi-gap Superconducting Josephson Junctions

Yukihiro Ota, Masahiko Machida, Tomio Koyama

摘要:

本文从理论上研究了由单能隙超导体和双能隙超导体构成的异质约瑟夫森结中的Shapiro台阶。我们发现,通过将外加微波的频率调谐到Josephson-Leggett模的频率,可以诱导出一个反常的直流Josephson电流,这在$I$ - $V$特性曲线中除了传统的Shapiro台阶外,还产生了一个额外的台阶结构.共振电压下的台阶高度呈现大小交替的结构,反映了双能隙超导体的能隙对称性。在$ \pm s波的情况下,其中两个间隙具有相反的符号在两个间隙超导体的步骤与奇数指数增强,而在s波的情况下,与偶数指数有较大的值。分数Shapiro步骤的存在也被预测。

英文摘要:

We theoretically study the Shapiro steps in a hetero Josephson junction made of a single-gap superconductor and a two-gap one. We find that an anomalous DC Josephson current is induced by tuning the frequency of an applied microwave to the Josephson-Leggett mode frequency, which creates an extra step structure in the $I$-$V$ characteristics besides the conventional Shapiro steps. The step heights at the resonance voltages exhibit an alternate structure of a large and small value reflecting the gap symmetry of the two-gap superconductor. In the $\pm s-wave case in which the two gaps have opposite signs in the two-gap superconductor the steps with odd index are enhanced, whereas in the s-wave case the ones with even index have larger values. The existence of the fractional Shapiro steps is also predicted.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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