Spin-orbital coupling effect on Josephson current through a superconductor heterojunction
Spin-orbital coupling effect on Josephson current through a superconductor heterojunction
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DOI：
10.1063/1.2927493
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发表时间：
2008-01
影响因子：
3.2
通讯作者：
Z. Yang;Y. Yang;J. Wang;K. S. Chan
中科院分区：
文献类型：
--
作者：
Z. Yang;Y. Yang;J. Wang;K. S. Chan
本文研究了超导体（SC）异质结对约瑟夫森电流的自旋-轨道耦合效应，该异质结由两个s波超导体和它们之间的二维电子气（2DEG）层组成。在2g区域考虑了自旋-轨道耦合的rashba型（RSOC）和/或dresselhaus型（DSOC）。利用紧密结合模型和格林函数法计算了流过结的直流超电流，发现临界电流Ic在SOC强度和层长均为2DEG时表现出阻尼振荡；特别是，RSOC和DSOC之间的强度比也可以诱导SC/2DEG/SC结在0状态和π状态之间切换。这种0-π跃迁源于这样一个事实，即二维系统中的SOC可以导致像铁磁体效应一样对流动的电子产生伪磁效应，因为系统的时间反转对称性已经被两个具有不同宏观相的SC引线打破。
We study the spin-orbital coupling effect on the Josephson current through a superconductor (SC) heterojunction, consisting of two s-wave superconductors and a two-dimensional electron gas (2DEG) layer between them. The Rashba-type (RSOC) and/or Dresselhaus-type (DSOC) of spin-orbital coupling are considered in the 2DEG region. By using a tight-binding model and Green’s function method, we calculate the dc supercurrent flowing through the junction and find that the critical current Ic exhibits a damped oscillation with both the strength of SOC and the layer length of 2DEG; especially, the strength ratio between RSOC and DSOC can also induce switching between the 0 state and the π state of the SC/2DEG/SC junction as well. This 0-π transition results from the fact that SOC in a two-dimension system can lead to a pseudomagnetic effect on the flowing electrons like the effect of a ferromagnet, since the time-reversal symmetry of the system has already been broken by two SC leads with different macroscopic phases.