Sensitivity of the superconducting state in thin films

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Thin-film superconductors often display an intermediate metallic state between superconducting and insulating phases.
• Existing theories struggle to explain this metallic state across various superconducting materials.

Purpose of the Study:

• To investigate the nature of the intermediate metallic state in thin-film superconductors.
• To determine if external factors influence this unusual metallic behavior.

Main Methods:

• Studied two distinct thin-film superconductors: amorphous indium oxide and 2H-NbSe2 single crystals.
• Systematically filtered external radiation incident on the superconductor samples.

Main Results:

• Elimination of the temperature-independent metallic state was achieved by filtering external radiation.
• Demonstrated that the metallic state arises from the extreme sensitivity of these films to external perturbations.
• Confirmed that superconductivity in two dimensions is only marginally stable.

Conclusions:

• The observed metallic state in thin-film superconductors is not an intrinsic phase but a consequence of sensitivity to external radiation.
• Filtering radiation provides a method to suppress this metallic state, offering insights into fundamental superconductivity mechanisms.
• Highlights the delicate stability of two-dimensional superconductivity.