Low-Temperature Stabilization of δ-NbN Superconducting Thin Films through Energy-Selective Ion Beam Sputtering
Abstract
Achieving high-quality superconducting thin films at low temperatures is a central challenge for scalable quantum device integration and Complementary Metal-Oxide-Semiconductor (CMOS)-compatible fabrication. Here, we demonstrate a room-temperature magnetron sputtering approach for synthesizing niobium nitride (NbN) thin films using a novel energy-selective ion source that enables independent control of ion energy and ion flux. This capability provides a powerful route to precisely tailor surface kinetics and crystallization pathways, overcoming longstanding limitations in stabilizing high-quality NbN at reduced temperatures. The resulting films were characterized by superconducting transport measurements, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Compared with conventional reactive sputtering, ion beam-assisted growth yields a substantial narrowing of the transition width at the superconducting temperature, indicating improved phase purity and electronic homogeneity. Furthermore, this work introduces energy-selective ion control as a general, non-equilibrium route to stabilize metastable superconducting phases at low temperatures, offering a new design paradigm for thin-film quantum materials.
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BibTeX
@misc{liu2026lowtemperature,
title = {{Low-Temperature Stabilization of $δ$-NbN Superconducting Thin Films through Energy-Selective Ion Beam Sputtering}},
author = {Yifan Liu and Junwoo Lee and Mingyu Xu and Weiwei Xie and Robert J. Cava and Qi Hua Fan},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.35091},
eprint = {2609.35091},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.35091},
}
RIS
TY - UNPB
TI - Low-Temperature Stabilization of δ-NbN Superconducting Thin Films through Energy-Selective Ion Beam Sputtering
AU - Yifan Liu
AU - Junwoo Lee
AU - Mingyu Xu
AU - Weiwei Xie
AU - Robert J. Cava
AU - Qi Hua Fan
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.35091
UR - https://arxiv.org/abs/2609.35091
AB - Achieving high-quality superconducting thin films at low temperatures is a central challenge for scalable quantum device integration and Complementary Metal-Oxide-Semiconductor (CMOS)-compatible fabrication. Here, we demonstrate a room-temperature magnetron sputtering approach for synthesizing niobium nitride (NbN) thin films using a novel energy-selective ion source that enables independent control of ion energy and ion flux. This capability provides a powerful route to precisely tailor surface kinetics and crystallization pathways, overcoming longstanding limitations in stabilizing high-quality NbN at reduced temperatures. The resulting films were characterized by superconducting transport measurements, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Compared with conventional reactive sputtering, ion beam-assisted growth yields a substantial narrowing of the transition width at the superconducting temperature, indicating improved phase purity and electronic homogeneity. Furthermore, this work introduces energy-selective ion control as a general, non-equilibrium route to stabilize metastable superconducting phases at low temperatures, offering a new design paradigm for thin-film quantum materials.
ER -