Quantum Nanoelectronics Seminar : Alexandra Palacio (INSP Jussieu)

Tuesday 26 June 2018 - 14h00 - Room « Remy Lemaire » (K223)

Real-Space Visualization of Majorana Edge Modes
on the Nano-Scale Magnet-Superconductor Hybrid System

Superconductivity and magnetism have been seen for a long time as antagonist until recent progress shows that their coupling leads to new phenomena. Specially, Majorana Fermions (MF) have attracted widespread interest for their promising potential for future applications in topological quantum computation. Advances in nano-fabrication techniques combined with local probe microscopies have paved the way to build up such hybrid systems and to analyze them at the nanoscale.

Recently, results on ferromagnetic chains [1] and ferromagnetic nanoislands [2] on a conventional superconductor revealing Yu-Shiba-Rusinov (YSR) bands were reported. These YSR bands are the precursors to observe MF modes at the edge of these hybrid systems at low dimensionality. However, the observation of these MF modes is still a subject of debate and has raised questions about experimental considerations that must be accounted. Lack of well-defined structures, MF spatial distribution and evolution inside the hybrid structures are among the reasons of these concerns. Hence, other combinations of superconductors and magnetic systems possibly holding MF such as non-collinear magnetic spin textures with well-defined structures should be investigated in order to deeply understand their physics.

Here, we present emergent phenomena appearing on the Fe magnetic nanowire with non-collinear spin textures on Re(0001) surface build up by atom manipulation [3]. Moreover, we report on the first unambiguous experimental detection and visualization of chiral Majorana edge states in a monolayer topological superconductor, a prototypical magnet-superconductor hybrid system comprised of nano-scale Fe islands of monoatomic height on a Re(0001)-O(2×1) surface [4, 5].

[1] S. Nadj-Perge et al., Science 346, 602 (2014)
[2] G. C. Ménard et al., Nat. Comm. (2017)
[3] H. Kim et al., Sci. Adv. 4, eaar5251 (2018)
[4] A. Palacio-Morales et al., Nano Lett. 16, 6252-6256 (2016)
[5] A. Palacio-Morales et al., submitted.

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