Evidence for a robust sign-changing s-wave order parameter in monolayer films of superconducting Fe (Se,Te)/Bi2Te3

Guannan Chen; Anuva Aishwarya; Mark R. Hirsbrunner; Jorge Olivares Rodriguez; Lin Jiao; Lianyang Dong; Nadya Mason; Dale Van Harlingen; John Harter; Stephen D. Wilson; Taylor L. Hughes; Vidya Madhavan

doi:10.1038/s41535-022-00513-y

npj Quantum Materials (Nov 2022)

Evidence for a robust sign-changing s-wave order parameter in monolayer films of superconducting Fe (Se,Te)/Bi2Te3

Guannan Chen,
Anuva Aishwarya,
Mark R. Hirsbrunner,
Jorge Olivares Rodriguez,
Lin Jiao,
Lianyang Dong,
Nadya Mason,
Dale Van Harlingen,
John Harter,
Stephen D. Wilson,
Taylor L. Hughes,
Vidya Madhavan

Affiliations

Guannan Chen: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
Anuva Aishwarya: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
Mark R. Hirsbrunner: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
Jorge Olivares Rodriguez: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
Lin Jiao: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
Lianyang Dong: Materials Department, University of California
Nadya Mason: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
Dale Van Harlingen: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
John Harter: Materials Department, University of California
Stephen D. Wilson: Materials Department, University of California
Taylor L. Hughes: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign
Vidya Madhavan: Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign

DOI: https://doi.org/10.1038/s41535-022-00513-y
Journal volume & issue: Vol. 7, no. 1
pp. 1 – 7

Abstract

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Abstract The Fe-based superconductor Fe (Se,Te) combines non-trivial topology with unconventional superconductivity and may be an ideal platform to realize exotic states such as high-order topological corner modes and Majorana modes. Thin films of Fe (Se,Te) are particularly important for device fabrication and phase sensitive transport measurements. While bulk Fe (Se,Te) has been extensively studied, the nature of the superconducting order parameter in the monolayer limit has not yet been explored. In this work, we study monolayer films of Fe (Se,Te) on Bi2Te3 with scanning tunneling spectroscopy. Monolayer Fe (Se,Te)/Bi2Te3 heterostructures host a multigap superconducting state that strongly resembles the bulk. Analysis of the phase-referenced quasiparticle interference signal reveals a sign-changing s-wave order parameter similar to the bulk as well as a unique pattern of sign changes which have not been observed in the bulk. Our work establishes monolayer Fe (Se,Te)/Bi2Te3 as a robust multi-band unconventional superconductor and sets the stage for explorations of non-trivial topology in this highly-tunable system.

Published in npj Quantum Materials

ISSN: 2397-4648 (Online)
Publisher: Nature Portfolio
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials; Science: Physics: Atomic physics. Constitution and properties of matter
Website: https://www.nature.com/npjquantmats/

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