论文标题
Zeeman和轨道效应对波纹石墨烯中约瑟夫森效应
Combined Zeeman and orbital effect on the Josephson effect in rippled graphene
论文作者
论文摘要
石墨烯约瑟夫森连接的二维性质提供了可能创建有效的超导体 - ferromagnet-superconductuctor连接,并由平面磁场引起的可调式Zeeman分裂。这样的连接将能够在常规的超导基态和具有内在相位差的基态之间交替,从而使它们可控$ 0-π$ josephson连接。但是,除了采面拆分外,由于石墨烯的高度变化,俗称纹波,平面磁场通常还会产生轨道效应。因此,Zeeman和轨道效应都会影响临界电流,因此,为了识别$ 0-π$转换,有必要了解它们的综合效果。从USADEL方程的分析和数值解决方案中,我们发现波纹实际上可以产生类似于$ 0-π$过渡的特征的电流响应。因此,为了揭示通过带有波纹的石墨烯中的旋转拆分引起的$ 0-π$过渡的存在,需要进行其他分析。在存在交换场和连锁反应的情况下,我们为临界电流提供了封闭形式的分析表达,以及具有连接参数的临界电流零的表达式。
The two-dimensional nature of graphene Josephson junctions offers the possibility of creating effective superconductor-ferromagnet-superconductor junctions with tunable Zeeman splitting caused by an in-plane magnetic field. Such junctions would be able to alternate between a conventional superconducting ground state and a ground state with an intrinsic phase difference, making them controllable $0-π$ Josephson junctions. However, in addition to the Zeeman splitting, an in-plane magnetic field will in general also produce an orbital effect because of height variations in graphene, colloquially known as ripples. Both the Zeeman and orbital effect will thus affect the critical current, so to be able to identify $0-π$ transitions it is necessary to understand their combined effect. From both analytical and numerical solutions of the Usadel equation we find that ripples can in fact produce a current response similar to that which is characteristic of a $0-π$ transition. Hence, additional analysis is required in order to reveal the presence of a $0-π$ transition caused by spin-splitting in graphene with ripples. We provide a closed form analytical expression for the critical current in the presence of exchange field and ripple effects as well as an expression for the scaling of critical current zeroes with junction parameters.