Distinguishing between topological Majorana and trivial zero modes via transport and shot noise study in an altermagnet heterostructure

Debashish Mondal, Amartya Pal, Arijit Saha, Tanay Nag
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Abstract

We theoretically investigate the transport and shot noise properties of a one-dimensional semiconducting nanowire with Rashba spin-orbit coupling~(SOC) placed in closed proximity to a bulk $s$-wave superconductor and an altermagnet with $d$-wave symmetry. Such heterostructure with vanishing net magnetization manifests itself as an alternative route to anchor Majorana zero modes~(MZMs) characterized by appropriate topological index~(winding number $W$). Interestingly, this system also hosts accidental zero modes~(AZMs) emerged with vanishing topological index indicating their non-topological nature. Furthermore, by incorporating three terminal setup, we explore the transport and shot noise signatures of these zero modes. At zero temperature, we obtain zero bias peak (ZBP) in differential conductance to be quantized with value $|W|\times 2 e^{2}/h$ for MZMs. On the other hand, AZMs exhibit non-quantized value at zero bias. Moreover, zero temperature shot noise manifests negative~(positive) value for MZMs~(AZMs) within the bulk gap. At finite temperature, shot noise exhibits negative value~(negative to positive transition) concerning MZMs~(AZMs). Thus, the obtained signatures clearly distinguish between the MZMs and non-topological AZMs. We extend our analysis by switching on the next to nearest neighbour hopping amplitude and SOC. Our conclusion remains unaffected for this case as well. Hence, our work paves the way to differentiate between emergent MZMs and AZMs in a semiconductor/ superconductor/ altermagnet heterostructure.
通过变磁性异质结构中的传输和射出噪声研究区分拓扑马约拉纳模式和微不足道的零模式
我们从理论上研究了一种具有拉什巴自旋轨道耦合(SOC)的一维半导体纳米线的输运和射噪声特性。这种具有消失净磁化的异质结构是锚定以适当拓扑指数(绕组数 $W$)为特征的马约拉纳零模(MZMs)的另一条途径。有趣的是,该系统还承载了意外零模(AZMs),其拓扑指数消失,表明其具有非拓扑性质。此外,通过结合三个终端设置,我们探索了这些零模的传输和射频噪声特征。在零温度下,我们得到了微分电导的零偏置峰值(ZBP),MZMs 的量子化值为$|W|\times 2 e^{2}/h$。 另一方面,AZMs 在零偏置时表现出非量子化值。此外,在体隙内,MZMs~(AZMs)的零温击穿噪声表现为负值~(正值)。在有限温度下,MZMs~(AZMs)的击穿噪声表现为负值~(负到正的转变)。我们通过切换近邻跳变振幅和 SOC 来扩展我们的分析。在这种情况下,我们的结论也不受影响。因此,我们的工作为区分半导体/超导体/异质磁体异质结构中出现的 MZM 和 AZM 铺平了道路。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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