Prof. Peng Wei
Department of Physics
University of California Riverside
Signature of a pair of Majorana zero modes in gold
Proximity effect in multilayer heterostructures allows the creation of new quasiparticles with mixed physical characters. In particular, it may lead to the emergence of Majorana zero modes
(MZM) by mixing superconductivity, ferromagnetism, and spin-orbit coupling at material interfaces. In this talk, I will present our work on searching for MZMs in the Shockley states at the (111)-terminated surface of gold. I will first discuss how we design the gold heterostructure to incorporate both superconductivity and magnetism. I will also show you our way of reducing the number of sub-bands or lowering the Fermi level of the gold surface states [1]. Based on this newly developed material platform, I will demonstrate our observation of MZM in islands of EuS – a ferromagnetic insulator epitaxially grown on gold surface [2]. I will discuss the topological transition of topological superconductivity, and the simultaneously emergence of a pair of MZMs when the applied magnetic field is increased. Finally, I will demonstrate a way to geometrically confine MZM at designated locations on gold surface. I will compare our experimental findings with theoretical modeling based on realistic parameters and show their good agreement to further confirm our observations.
[1] Wei, P., S. Manna, et al., "Superconductivity in the surface state of noble metal gold and its Fermi level tuning by EuS dielectric." Phys Rev Lett 122(24): 247002 (2019).
[2] Manna, S., P. Wei, et al., "Signature of a pair of Majorana zero modes in superconducting gold surface states." PNAS: 10.1073/pnas.1919753117 (2020).
All interested persons are invited to attend remotely—email physics@nd.edu for information.