Superconductivity on Edge: Evidence of a One-Dimensional Superconducting Channel at the Edges of Single-Layer FeTeSe Antiferromagnetic Nanoribbons.

Ge, Zhuozhi; Zou, Qiang; Zhang, Huimin; Yan, Chenhui; Agterberg, Daniel; Weinert, Michael; Li, Lian · ACS Nano · 2020

basic_science · Level V

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Abstract

How superconductivity emerges from antiferromagnetic ordering is an essential question for Fe-based superconductors. Here, we explore the effect of dimensionality on the interplay between antiferromagnetic ordering and superconductivity by investigating nanoribbons of single-layer FeTe<sub>1-<i>x</i></sub>Se<sub><i>x</i></sub> films grown on SrTiO<sub>3</sub>(001) substrates by molecular beam epitaxy. Using scanning tunneling microscopy/spectroscopy, we find a one-dimensional (1D) superconducting channel 2 nm wide with a <i>T</i><sub>C</sub> of 42 ± 4 K on the edge of FeTe<sub>1-<i>x</i></sub>Se<sub><i>x</i></sub> (<i>x</i> < 0.1) ribbons, coexisting with a non-superconducting ribbon interior that remains bicollinear antiferromagnetically ordered. Density functional theory calculations indicate that both Se and the presence of the edge destabilize the bicollinear antiferromagnetic magnetic order, resulting in a paramagnetic region near the edge with strong local checkerboard fluctuations that is conducive to superconductivity. Our results represent the highest <i>T</i><sub>C</sub> achieved in 1D superconductors and demonstrate an effective route toward stabilizing superconductivity in Fe-based superconductors at reduced dimensions.