SPICE Workshop on Hybrid Correlated States and Dynamics in Quantum Materials, May 14th - 16th 2024
Shawulienu Kezilebieke
Designer materials are a key research subject in condensed matter physics offering great opportunities to explore emerging new physics and provide pathways to many-body quantum phenomena that are exceedingly difficult to find intrinsically in isolated materials. One of the interesting class of materials are topological superconductors, they are a class of superconducting materials characterized by sub-gap zero energy localized modes, known as Majorana boundary states (MBSs). These materials are promising for the development of quantum computing technology. However, it is unclear whether topological superconductivity exists in any naturally occurring materials. The problem can be circumvented by deliberately selecting the combination of materials in heterostructures so that the desired physics emerges from interactions between the different components. There are many routes to realizing topological superconductivity in artificial structures, and perhaps the most widely used path uses the combination of superconductivity, spin-orbit coupling, and magnetism.
In this talk, I will give a brief introduction to two artificial platforms that can host topological superconductivity: 1D ferromagnetic atomic chain and 2D van der Waals (vdW) ferromagnet on a superconducting substrate.
I will discuss our research towards this aim using molecular beam epitaxy (MBE) and low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). We use MBE to grow islands of ferromagnetic CrBr3 on a superconducting NbSe2 substrate. This combines out-of-plane ferromagnetism with Rashba spin-orbit interactions and s-wave superconductivity and allows us to realizate topological superconductivity in a van der Waals heterostructure. We characterize the resulting one-dimensional edge modes using STM and STS. I am also going to talk about how the moire pattern between a van der Waals superconductor and a monolayer ferromagnet will affect the topological superconductivity of the heterostructure.
References
[1] M. Sato, and Y. Ando, Topological superconductors: a review. Rep. Prog. Phys. 80, 076501(2017).[2] S. Kezilebieke, M. N. Huda, V. Vano, M. Aapro, S.C. Ganguli, O.J. Silveira, S. Glodzik, A.S. Foster, T. Ojanen, P. Liljeroth, Nature 588 (7838), 424-428.
[3] S. Kezilebieke, V. Vano, M. N. Huda, M. Aapro, S.C. Ganguli, P. Liljeroth, Jose L. Lado, Nano Lett. 2022, 22, 1, 328–333