Leiden Institute of Physics, Leiden University, 2333 CA, Leiden, The Netherlands.
Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ, Delft, The Netherlands.
Nat Commun. 2023 Jun 8;14(1):3341. doi: 10.1038/s41467-023-39109-w.
Majorana bound states are putative collective excitations in solids that exhibit the self-conjugate property of Majorana fermions-they are their own antiparticles. In iron-based superconductors, zero-energy states in vortices have been reported as potential Majorana bound states, but the evidence remains controversial. Here, we use scanning tunneling noise spectroscopy to study the tunneling process into vortex bound states in the conventional superconductor NbSe, and in the putative Majorana platform FeTeSe. We find that tunneling into vortex bound states in both cases exhibits charge transfer of a single electron charge. Our data for the zero-energy bound states in FeTeSe exclude the possibility of Yu-Shiba-Rusinov states and are consistent with both Majorana bound states and trivial vortex bound states. Our results open an avenue for investigating the exotic states in vortex cores and for future Majorana devices, although further theoretical investigations involving charge dynamics and superconducting tips are necessary.
马约拉纳束缚态是固体中假定的集体激发态，它们表现出马约拉纳费米子的自共轭性质——它们是自己的反粒子。在铁基超导体中，涡旋中的零能态被报道为潜在的马约拉纳束缚态，但证据仍存在争议。在这里，我们使用扫描隧道噪声光谱来研究传统超导体 NbSe 和假定的马约拉纳平台 FeTeSe 中进入涡旋束缚态的隧道过程。我们发现，两种情况下进入涡旋束缚态的隧道都表现出单个电子电荷的电荷转移。我们在 FeTeSe 中的零能束缚态的数据排除了 Yu-Shiba-Rusinov 态的可能性，并且与马约拉纳束缚态和平凡涡旋束缚态都一致。我们的结果为研究涡旋核中的奇异态和未来的马约拉纳器件开辟了途径，尽管需要进一步涉及电荷动力学和超导尖端的理论研究。
