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Structural and electronic inhomogeneity of superconducting Nb-doped Bi2Se3

DOI: 10.1103/PhysRevB.103.085107 DOI Help

Authors: Simone M. Kevy (Aarhus University) , Henriette E. Lund (Aarhus University) , Laura Wollesen (Aarhus University) , Kirstine J. Dalgaard (Aarhus University) , Yu-te Hsu (Radboud University) , Steffen Wiedmann (Radboud University) , Marco Bianchi (Aarhus University) , Ann Julie Utne Holt (Aarhus University) , Davide Curcio (Aarhus University) , Deepnarayan Biswas (Aarhus University) , Alfred J. H. Jones (Aarhus University) , Klara Volckaert (Aarhus University) , Cephise Cacho (Diamond Light Source) , Pavel Dudin (Diamond Light Source) , Philip Hofmann (Aarhus University) , Martin Bremholm (Aarhus University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 103

State: Published (Approved)
Published: February 2021
Diamond Proposal Number(s): 20218

Abstract: The crystal structure, electronic structure, and transport properties of crystals with the nominal composition Nb 0.25 Bi 2 Se 3 are investigated. X-ray diffraction reveals that the as-grown crystals display phase segregation and contain major contributions of BiSe and the superconducting misfit layer compound ( Bi Se ) 1.1 Nb Se 2 . The inhomogeneous character of the samples is also reflected in the electronic structure and transport properties of different single crystals. Angle-resolved photoemission spectroscopy (ARPES) reveals an electronic structure that resembles poor-quality Bi 2 Se 3 with an ill-defined topological surface state. High-quality topological surface states are instead observed when using a highly focused beam size, i.e., nanoARPES. While the superconducting transition temperature is found to vary between 2.5 and 3.5 K, the majority of the bulk single crystals does not exhibit a zero-resistance state suggesting filamentary superconductivity in the materials. Susceptibility measurements of the system together with the temperature dependence of the coherence length extracted from the upper critical field are consistent with conventional BCS superconductivity of a type II superconductor.

Journal Keywords: Crystal growth; Crystal stoichiometry; Crystal structure; Electrical conductivity; Electronic structure; Interstitials; Magnetic susceptibility; Magnetotransport; Proximity effect; Shubnikov-de Haas effect; Structural properties; Superconductors; Surface

Subject Areas: Materials, Physics

Instruments: I05-ARPES

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