Full-Gap Superconductivity in BaAs/Ferropnictide Heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity

Background:

• Interfacial interactions in 2D systems can lead to unusual phenomena like high-temperature superconductivity.
• Ferropnictide materials, such as Ba(Fe_{1-x}Co_{x})_{2}As_{2} (BFCA), are known for their superconducting properties.
• Standalone BFCA thin films show rapid suppression of critical temperature (Tc) with reduced thickness.

Purpose of the Study:

• To investigate superconductivity in a BaAs monolayer grown on BFCA epitaxial films.
• To understand the role of interfacial interactions and heterostructure crystallinity on superconductivity.
• To explore the robustness of superconductivity against reduced substrate thickness.

Main Methods:

• Epitaxial growth of BaAs monolayer on BFCA films.
• Spectroscopic measurements to determine superconducting properties.
• Analysis of heterostructure crystallinity, electronic, and geometric uniformity.

Main Results:

• Observation of full-gap superconductivity in BaAs/BFCA heterostructures with a maximal spectroscopic temperature up to 26 K.
• Superconducting gap robustness even when the underlying BFCA is reduced to a monolayer.
• Correlation between exceptional heterostructure crystallinity and emergent superconductivity.

Conclusions:

• Exceptional crystallinity and uniformity of BaAs/BFCA heterostructures are crucial for robust, full-gap superconductivity.
• The observed superconductivity exhibits mean-field temperature dependence and bound states within magnetic vortices.
• Findings advance the understanding of unconventional superconductivity in ferropnictides and FeAs-based heterostructures.