Losses in superconducting Niobium Films caused by Interface Tunnel Exchange

TL;DR

This paper investigates the loss mechanisms in superconducting niobium films, revealing that interface tunneling between surface oxides and niobium's superconducting states is a key contributor to energy losses.

Contribution

It identifies interface tunnel exchange as a significant loss mechanism in niobium films, providing insights for improving superconducting cavity performance.

Findings

Electric field is a dominant loss mechanism.

Loss occurs via interface tunneling between surface oxides and niobium.

Results inform future mitigation strategies for superconducting cavities.

Abstract

Identifying the loss mechanisms of niobium film cavities enables an accurate determination of applications for future accelerator projects and points to research topics required to mitigate their limitations. Measurements on samples show that the electric field is a dominant loss mechanism for niobium films, acting through interface tunneling between localized states in surface oxides and delocalized states in the superconducting niobium.