Increasing the superconductivity of TiN epitaxial films by lattice strain toward a record critical temperature
Phys. Rev. B 112, 045403 – Published 7 July, 2025
DOI: https://doi.org/10.1103/vk73-drrn
Abstract
The full understanding of superconductivity in titanium nitride (TiN) is fundamentally important for advancing both nitride physics and high-performance superconducting quantum devices. However, further increasing its superconducting critical temperature remains a considerable challenge. In this study, we synthesized a series of high-quality TiN films with varying lattice parameters and tunable superconducting critical temperatures. Low-temperature electrical transport measurements reveal that the superconducting transition temperatures of TiN films can be increased from 5.3 to 5.7 K, a record value in the peer-reviewed literature. High-resolution x-ray diffraction analysis indicates that this increase in superconducting critical temperatures can be attributed to lattice strain. Furthermore, density functional theory calculations demonstrate that the lattice strain can effectively tune the superconductivity of TiN films by controlling the strength of the electron-phonon interaction. Our findings offer an approach to tailoring the superconducting transition temperatures of TiN films, thereby laying the groundwork for further advancements in both nitride physics and high-performance superconducting quantum devices.
