Crossover from Ising to Rashba Superconductivity in Epitaxial Bi2Se3/Monolayer NbSe2 Heterostructures


Contributed by: Joshua Robinson, Chao-Xing Liu, and Cui-Zu Chang

Yi et al, Nature Materials 21,1366 (2022). 

An IRG team developed a synthesis approach to combine two materials with distinct properties: monolayer Ising superconductor NbSe2 and topological insulator Bi2Se3. This heterostructure enables the exploration of a unique form of superconductivity known as topological superconductivity, which is predicted to be foundational to the development of topological quantum computation.

The team used molecular beam epitaxy, the deposition of atoms onto surfaces in ultrahigh vacuum conditions, to grow superconducting Bi2Se3/monolayer NbSe2 heterostructures  with different Bi2Se3 thicknesses. Gapless Dirac surface states and Rashba-type bulk bands were both observed. The emergence of these features coincides with a suppression of the in-plane upper critical magnetic field. This is a signature of a crossover from Ising to Rashba  superconducting pairing.

The establishment of molecular beam epitaxy growth of both Ising-type superconductor and topological insulator films will advance the exploration of robust topological superconductivity


What Has Been Achieved:  Fabrication of superconducting Bi2Se3 on monolayer NbSe2 heterostructures using all-MBE methods.

Importance of the Achievement: The successful synthesis of both Ising-type superconductor and topological insulator (TI) films by MBE as well as the observation of crossover from Ising-type to bulk Rashba-type superconductivity may advance the exploration of the robust topological superconductivity phase in TI/Ising-type superconductor heterostructures.

How is the achievement related to the IRG, and how does it help it achieve its goals? Our research team benefits from close collaboration within the IRG team. The experimentalists have investigated a hybridized structure consisting of two crystalline materials. The resulting heterostructure displays novel physical properties, which have been well explained by theoretical analysis. This system has the potential to serve as topological superconductors for quantum computing applications.

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