Interfacial superconductivity in Fe-chalcogenide/topological insulator heterostructures

Iron-chalcogenide based superconductor have set a new paradigm in exploring microscopic mechanism of superconductivity and a race to discover high-T_c interfacial superconductor. It also offer a new platform to realize pristine topological superconductivity and Majorana bound state at relatively high temperature [1, 2]. 

In this talk, I will discuss our recent findings of atomic scale spin structure and superconductivity in single layer Fe-chalcogenide films grown on Bi-based 3D topological insulator, briefly explained as follows. At first, we show the existence of non-collinear antiferromagnetic state in a single unit-cell FeTe, as revealed by spin-polarized scanning tunnelling spectroscopy. A detailed investigation of the temperature, magnetic field and spatial evolution of the electronic structure across the magnetic domains indicates that the unit-cell of FeTe is in very close proximity to a superconducting phase transition that coexisting with the anti-ferromagnetism [3, 4]. This will followed by discussion in spatial distribution of superconductivity in single layer FeSe_0.5Te_0.5 with higher critical temperature, which provides an ideal platform to study exotic phase in close proximity to a topological insulator [5].

Finally, I will discuss our unique approach to create a metallic based topological superconductor in combination with surface state of large Rashba spin-orbit coupling and an S-wave superconductor.

Research in collaboration with J. Wiebe, R. Wiesendanger, P. Wei, P. A. Lee and J. Moodera, supported by ERC advanced grant & JT foundation.

References

1.     G. Xu et al., Phys. Rev. Lett. 117, 047001 (2016).

2.     D. Wang et al., Arxiv: 1706.06074. 

3.     S. Manna et al., Nature Comm. 8, 14074 (2017).

4.     T. Hänke et al., Nature Comm.  8, 13939 (2017).

5.     A. Kamlapure et al., Phys. Rev. B   95, 104509 (2017).