Crossover of Ising- to Rashba-Type Superconductivity in Epitaxial Bi2Se3/Monolayer NbSe2 Heterostructures

Abstract

A topological insulator (TI) interfaced with an s-wave superconductor has been predicted to host an unusual form of superconductivity known as topological superconductivity (TSC). Molecular beam epitaxy (MBE) has been the primary approach in the scalable synthesis of the TI/superconductor heterostructures. Although the growth of epitaxial TI films on s-wave superconductors has been achieved, it remains an outstanding challenge for synthesizing atomically thin TI/superconductor heterostructures, which are critical for engineering the TSC phase. Here, we used MBE to grow Bi2Se3 films with the controlled thickness on monolayer NbSe2 and performed in-situ angle-resolved photoemission spectroscopy and ex-situ magneto-transport measurements on these Bi2Se3/monolayer NbSe2 heterostructures. We found that the emergence of Rashba-type bulk quantum well bands and spin-nondegenerate surface states coincides with a marked suppression of the in-plane upper critical magnetic field of the superconductivity in Bi2Se3/monolayer NbSe2 heterostructures. This is the signature of a crossover from Ising- to Rashba-type superconducting pairings, induced by altering Bi2Se3 film thickness. Our work opens a new route for exploring a robust TSC phase in TI/Ising superconductor heterostructures.

27 pages, 4 pages, comments are welcome

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• Topological Fermi-arc surface state covered by floating electrons on a two-dimensional electride
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• Spin-orbit-coupled superconductivity with spin-singlet non-unitary pairing
• Superconducting diode effect in Ising superconductors
• Growth of bilayer stanene on a magnetic topological insulator aided by a buffer layer
• Atomically-precise synthesis and simultaneous integration of 2D transition metal dichalcogenides enabled by nano-confinement
• Unconventional pairing in Ising superconductors: Application to monolayer NbSe${}_2$
• Constructing the Fulde-Ferrell-Larkin-Ovchinnikov state in antiferromagnetic insulator CrOCl
• Dynamical Hall responses of disordered superconductors
• Ultrafast switching of topological invariants by light-driven strain
• Control of nonreciprocal charge transport in topological insulator/superconductor heterostructures with Fermi level tuning and superconducting-layer thickness
• Possible Topological Superconductivity in a Topological Crystalline Insulator (Pb${}_{1-x}$Sn${}_x$)${}_{1-y}$In${}_y$Te
• Interface-Enhanced Superconductivity in Ultrathin TiN Proximitized by Topological Insulators
• Nucleation and Antiphase Twin Control in Bi${}_2$Se${}_3$ via Step-Terminated Al${}_2$O${}_3$ Substrates
• Observation of the crossover from quantum fluxoid to half-quantum fluxoid in a chiral superconducting device
• Two-dimensional helical superconductivity and gapless superconducting edge modes in the 1T${}^{\prime }$-WS${}_2$/2H-WS${}_2$ heterophase bilayer