Atomic Diffusion-Induced Polarization and Superconductivity in Topological Insulator-Based Heterostructures

ACS Nano, vol. 18, pp. 571–580

Abstract

High Resolution Image Download MS PowerPoint Slide The proximity effect at a highly transparent interface of an s -wave superconductor (S) and a topological insulator (TI) provides a promising platform to create Majorana zero modes in artificially designed heterostructures. However, structural and chemical issues pertinent to such interfaces have been poorly explored so far. Here, we report the discovery of Pd diffusion-induced polarization at interfaces between superconductive Pd 1+ x (Bi 0.4 Te 0.6 ) 2 ( x PBT, 0 ≤ x ≤ 1) and Pd-intercalated Bi 2 Te 3 by using atomic-resolution scanning transmission electron microscopy. Our quantitative image analysis reveals that nanoscale lattice strain and QL polarity synergistically suppress and promote Pd diffusion at the normal and parallel interfaces, formed between Te–Pd–Bi triple layers (TLs) and Te–Bi–Te–Bi–Te quintuple layers (QLs), respectively. Further, our first-principles calculations unveil that the superconductivity of the x PBT phase and topological nature of the Pd-intercalated Bi 2 Te 3 phase are robust against the broken inversion symmetry. These findings point out the necessity of considering the coexistence of electric polarization with superconductivity and topology in such S–TI systems.

Authors 7

1. Xian‐Kui Wei corresponding

   Forschungszentrum Jülich · Ernst Ruska Centre

   Affiliation as printed

   Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

2. Abdur Rehman Jalil

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Peter Grünberg Institute and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

3. Philipp Rüßmann corresponding

   Forschungszentrum Jülich · Jülich Aachen Research Alliance · University of Würzburg

   Affiliation as printed

   Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany

   Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA, 52425 Jülich, Germany

4. Yoichi Ando

   University of Cologne

   Affiliation as printed

   Physics Institute II, University of Cologne, Zülpicher Straße 77, 50937 Köln, Germany

5. Detlev Grützmacher

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Peter Grünberg Institute and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

6. Stefan Blügel

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA, 52425 Jülich, Germany

7. Joachim Mayer Aachen Central Facility for Electron Microscopy

   RWTH Aachen University · Forschungszentrum Jülich · Ernst Ruska Centre

   Affiliation as printed

   Central Facility for Electron Microscopy, RWTH Aachen University, Ahornstraße 55, 52074 Aachen, Germany

   Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany