Estrada Saldaña J C, Žitko R, Cleuziou J P, Lee E J H, Zannier V, Ercolani D, Sorba L, Aguado R, De Franceschi S
Université Grenoble Alpes, CEA, INAC-PHELIQS, 38000 Grenoble, France.
Jožef Stefan Institute, Jamova 39, Ljubljana, Slovenia.
Sci Adv. 2019 Jul 5;5(7):eaav1235. doi: 10.1126/sciadv.aav1235. eCollection 2019 Jul.
A semiconductor nanowire with strong spin-orbit coupling in proximity to a superconductor is predicted to display Majorana edge states emerging under a properly oriented magnetic field. The experimental investigation of these exotic states requires assessing the one-dimensional (1D) character of the nanowire and understanding the superconducting proximity effect in the presence of a magnetic field. Here, we explore the quasi-ballistic 1D transport regime of an InAs nanowire with Ta contacts. Fine-tuned by means of local gates, the observed plateaus of approximately quantized conductance hide the presence of a localized electron, giving rise to a lurking Coulomb blockade effect and Kondo physics. When Ta becomes superconducting, this local charge causes an unusual, reentrant magnetic field dependence of the supercurrent, which we ascribe to a 0 - π transition. Our results underline the relevant role of unintentional charge localization in the few-channel regime where helical subbands and Majorana quasi-particles are expected to arise.
据预测，在靠近超导体的情况下具有强自旋轨道耦合的半导体纳米线，在适当取向的磁场下会出现马约拉纳边缘态。对这些奇异态进行实验研究需要评估纳米线的一维（1D）特性，并了解存在磁场时的超导邻近效应。在这里，我们探索了具有Ta接触的InAs纳米线的准弹道一维输运 regime。通过局部栅极进行微调，观察到的近似量子化电导的平台隐藏了局域电子的存在，从而产生了潜在的库仑阻塞效应和近藤物理现象。当Ta变成超导体时，这种局部电荷会导致超电流出现异常的、重入的磁场依赖性，我们将其归因于0 - π转变。我们的结果强调了在预期会出现螺旋子带和马约拉纳准粒子的少通道 regime中，非故意电荷局域化的相关作用。
