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 are poorly explored so far. Here, we report the discovery of Pd diffusion induced polarization at interfaces between superconductive Pd1+x(Bi0.4Te0.6)2 (xPBT, 0≤x≤1) and Pd-intercalated Bi2Te3 by using atomic-resolution scanning transmission electron microscopy. Our quantitative image analysis reveals that nanoscale lattice strain and QL polarity synergistically suppress and promote the 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 xPBT phase and topological nature of Pd-intercalated Bi2Te3 phase are robust against the broken inversion symmetry. These findings point out the necessity of considering coexistence of electric polarization with superconductivity and topology in such S-TI systems.
@article{arxiv.2311.16590,
title = {Atomic diffusion-induced polarization and superconductivity in topological insulator-based heterostructures},
author = {Xian-Kui Wei and Abdur Rehman Jalil and Philipp Rüßmann and Yoichi Ando and Detlev Grützmacher and Stefan Blügel and Joachim Mayer},
journal= {arXiv preprint arXiv:2311.16590},
year = {2024}
}