Phase fluctuations dominated superconductivity in a thick Granular Boron-Doped Diamond film
Abstract
We investigate the superconducting properties of a 1.2-μm-thick granular boron-doped diamond film, where tightly packed grains form a disordered network of Josephson junctions. The film exhibits a sharp superconducting transition at a critical temperature, T_c ~ 3 K. Its transport properties are well described by the Ambegaokar-Halperin theory of phase fluctuations. Direct measurements of the penetration depth using a two-coil mutual inductance technique reveal classic phase-fluctuation-dominated behavior: below T_c, the superfluid density (n_s) varies linearly over a wide temperature range - a hallmark of thermal phase fluctuations - before crossing over to a T^2 dependence at ultra-low temperatures. Both the large low-temperature penetration depth, λ(0) ~ 8.8 μm, and the slope of the linear ns variation in the thermal regime reveal a remarkably low superfluid stiffness in the range of 0.5-0.8 K. These results establish granular boron-doped diamond films as an excellent model system for investigating the role of long-wavelength phase fluctuations in three-dimensional superconductors.
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BibTeX
@misc{dutta2026phase,
title = {{Phase fluctuations dominated superconductivity in a thick Granular Boron-Doped Diamond film}},
author = {Sulagna Dutta and Subhajit Chatterjee and Vivas Bagwe and Pritam Das and S. Anantha Bharathi and C. Nikhil and M. S. Ramachandra Rao and Pratap Raychaudhuri},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.34319},
eprint = {2610.34319},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.34319},
}
RIS
TY - UNPB
TI - Phase fluctuations dominated superconductivity in a thick Granular Boron-Doped Diamond film
AU - Sulagna Dutta
AU - Subhajit Chatterjee
AU - Vivas Bagwe
AU - Pritam Das
AU - S. Anantha Bharathi
AU - C. Nikhil
AU - M. S. Ramachandra Rao
AU - Pratap Raychaudhuri
PY - 2026
DA - 2026/10/25
PB - arXiv
DO - 10.48550/arxiv.2610.34319
UR - https://arxiv.org/abs/2610.34319
AB - We investigate the superconducting properties of a 1.2-μm-thick granular boron-doped diamond film, where tightly packed grains form a disordered network of Josephson junctions. The film exhibits a sharp superconducting transition at a critical temperature, T_c ~ 3 K. Its transport properties are well described by the Ambegaokar-Halperin theory of phase fluctuations. Direct measurements of the penetration depth using a two-coil mutual inductance technique reveal classic phase-fluctuation-dominated behavior: below T_c, the superfluid density (n_s) varies linearly over a wide temperature range - a hallmark of thermal phase fluctuations - before crossing over to a T^2 dependence at ultra-low temperatures. Both the large low-temperature penetration depth, λ(0) ~ 8.8 μm, and the slope of the linear ns variation in the thermal regime reveal a remarkably low superfluid stiffness in the range of 0.5-0.8 K. These results establish granular boron-doped diamond films as an excellent model system for investigating the role of long-wavelength phase fluctuations in three-dimensional superconductors.
ER -