Magnetism- and impurity-assisted chain creation in Ir and Pt break junctions

TL;DR

This study models how light impurities and magnetic effects influence the formation, stability, and elongation of Pt and Ir atomic chains in break junctions, revealing impurity-specific impacts on chain properties.

Contribution

It introduces a detailed model incorporating impurities, magnetism, and spin-orbit effects to analyze chain formation in break junctions, supported by first-principles parameters.

Findings

Impurities significantly alter chain binding and elongation.

s-like impurities reduce chain stability.

Magnetism and spin-orbit interactions affect chain growth.

Abstract

Applying the generalization of the model for chain formation in break-junctions [JPCM 24, 135501 (2012)], we study the effect of light impurities on the energetics and elongation properties of Pt and Ir chains. Our model enables us with a tool ideal for detailed analysis of impurity assisted chain formation, where zigzag bonds play an important role. In particular we focus on H (s-like) and O (p-like) impurities and assume, for simplicity, that the presence of impurity atoms in experiments results in ..M-X-M-X-... (M: metal, X: impurity) chain structure in between the metallic leads. Feeding our model with material-specific parameters from systematic full-potential first-principles calculations, we find that the presence of such impurities strongly affects the binding properties of the chains. We find that while both types of impurities enhance the probability of chains to be elongated, the s-like impurities lower the chain's stability. We also analyze the effect of magnetism and spin-orbit interaction on the growth properties of the chains.