ONLINE - PhD Mid-term Seminar Series: Magnetic interaction between Mn atoms on the superconductor -Bi2Pd revealed by their Yu-Shiba-Rusinov States

CIC nanoGUNE Seminars

Stefano Trivini, Nanoimaging Group
nanoGUNE online Webinar
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ONLINE - PhD Mid-term Seminar Series: Magnetic interaction between Mn atoms on the superconductor -Bi2Pd revealed by their Yu-Shiba-Rusinov States **** **Magnetic interaction between Mn atoms on the superconductor -Bi 2Pd revealed by their Yu-Shiba-Rusinov States** Stefano Trivini Nanoimaging Group, CIC nanoGUNE In the last decade, the interest in studying the coupling between magnetic atoms arranged in linear chains on superconducting surfaces increased.1,2,3 This is due to proposals suggesting emergence of Majorana bound states (MBS) in condensed matter systems, that have potential applications in topological quantum computing.4 A powerful way to investigate the coupling is looking at how it modifies the Yu-Shiba-Rusinov (YSR) states inside the superconducting gap. These states are generated by the exchange coupling between a magnetic impurity and the Cooper pair condensate of the superconductor.5 The coupling mechanism can be investigated by monitoring the sub gap YSR fingerprint during the construction of atomically precise structures. We cited studies that report evidence of Majorana bound states. However, more control on the atomic precision and the spectral resolution is needed to understand the coupling mechanism and to distinguish trivial magnetic states (YSR) from topological states (MBS). By means of a low temperature scanning tunneling microscope (STM) working at 1.3K, we perform atomic manipulation of Mn atoms on -Bi2Pd superconductor (Tc=5.4K, =0.78mV). A major advantage is achieved doing atomic manipulation with superconductive tips, studying the coupling with high resolution in Mn dimers, trimers, cross like structures, chains and other more complex structures. Depending on the distance and geometry different coupling effects occurs, with signatures of ferromagnetic and antiferromagnetic coupling. Growing linear chains, we have evidence of a collective behavior with a lowering in energy of the YSR states that saturates for chains longer than 6-7 atoms. The substrate inhomogeneities also effect the YSR states, underlying the importance of controlling this parameter when building structures. **References** 1. Nadj-Perge, S., Drozdov, I. K., Bernevig, B. A. & Yazdani, A. Proposal for realizing Majorana fermions in chains of magnetic atoms on a superconductor. Phys. Rev. B **88** , 020407 (2013). 2. Nadj-Perge, S. et al. Observation of Majorana fermions in ferromagnetic atomic chains on a superconductor. Science **346** , 602–607 (2014). 3. Kim, H. et al. Toward tailoring Majorana bound states in artificially constructed magnetic atom chains on elemental superconductors. Sci. Adv. **4** , eaar5251 (2018). 4. Alicea, J., Oreg, Y., Refael, G., von Oppen, F. & Fisher, M. P. A. Non-Abelian statistics and topological quantum information processing in 1D wire networks. Nat. Phys. **7** , 412–417 (2011). 5. Heinrich, B. W., Pascual, J. I. & Franke, K. J. Single magnetic adsorbates on s -wave superconductors. Prog. Surf. Sci. **93** , 1–19 (2018). \---------- Please **REGISTER** for PhD Mid-term Seminar Series on Sep 7, 2020 11:00 AM CEST at: After registering, you will receive a confirmation email containing information about joining the webinar. Thank you very much for your participation!