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arXiv 1701.03589cond-mat.supr-con
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磁场和Rashba自旋轨道相互作用对超导纳米线间Josephson隧穿的影响

Effect of Magnetic Field and Rashba Spin-Orbit Interaction on the Josephson Tunneling between Superconducting Nanowires

E. Nakhmedov, O. Alekperov, F. Tatardar, Yu. M. Shukrinov, I. Rahmonov, K. Sengupta

摘要:

我们计算了两个一维(1D)纳米线之间的约瑟夫森电流沿$x$与邻近诱导$s$波超导配对,并通过一个狭窄的电介质势垒的存在下,Rashba自旋轨道相互作用(SOI)的特点是强度$α$和塞曼场($h$沿$\hat z$和${\bf B}$在$x-y$平面)。我们制定了一个通用的方法来计算Andreev束缚态的能量,使我们能够获得这些状态的能量在几个渐近的情况下的解析表达式。我们发现,在没有磁场的情况下,Andreev束缚态之间的能隙随着Rashba SOI常数的增加而减小,最终导致能级的接触。在没有Rashba SOI的情况下,Andreev束缚态依赖于磁场,并且随着取向角B的变化而呈现振荡行为,导致磁约瑟夫森效应。我们还提出了解析表达式的直流约瑟夫森电流绘制出它们的依赖于${\bf B}$,$h$,和$α$。我们证明了在外加磁场的存在下,这些结中存在有限的自旋约瑟夫森电流,并提供了其对$α$,$\bf B$和$h$的依赖关系的解析表达式。最后,我们研究了交流约瑟夫森效应中存在的SOI($|{\bf B}|=h=0$)和外部辐射,并表明,在这样的系统中产生的夏皮罗步骤的宽度可以通过改变$α$。我们讨论的实验,可以测试我们的理论结果。

英文摘要:

We calculate the Josephson current between two one-dimensional (1D) nanowires oriented along $x$ with proximity induced $s$-wave superconducting pairing and separated by a narrow dielectric barrier in the presence of both Rashba spin-orbit interaction (SOI) characterized by strength $α$ and Zeeman fields ($h$ along $\hat z$ and ${\bf B}$ in the $x-y$ plane). We formulate a general method for computing the Andreev bound states energy which allows us to obtain analytical expressions for the energy of these states in several asymptotic cases. We find that in the absence of the magnetic fields the energy gap between the Andreev bound states decreases with increasing Rashba SOI constant leading eventually to touching of the levels. In the absence of Rashba SOI, the Andreev bound states depend on the magnetic fields and display oscillatory behavior with orientational angle of B leading to magneto-Josephson effect. We also present analytic expressions for the dc Josephson current charting out their dependence on ${\bf B}$, $h$, and $α$. We demonstrate the existence of finite spin-Josephson current in these junctions in the presence of external magnetic fields and provide analytic expressions for its dependence on $α$, $\bf B$ and $h$. Finally, we study the AC Josephson effect in the presence of the SOI (for $|{\bf B}|=h=0$) and an external radiation and show that the width of the resulting Shapiro steps in such a system can be tuned by varying $α$. We discuss experiments which can test our theoretical results.

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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