Chemical Substitution as a Route to Anomalous Surface Superconductivity in NiBi3
Abstract
Stabilizing two-dimensional superconductivity in a bulk superconducting material provides a unique route to exploring the interplay between superconducting condensates of different dimensionalities. Here, we present evidence for a distinct surface-associated superconducting state in Pb-substituted NiBi3. NiBi2.8Pb0.2 exhibits a resistive onset at Tc,onset*≈8.1~K, nearly twice the bulk superconducting transition temperature of approximately 4.1~K. The absence of a corresponding Meissner response or specific-heat anomaly at the higher-temperature transition supports its non-bulk origin. A cusp-like angular dependence of the critical field, well described by the two-dimensional Tinkham model, together with nonlinear current--voltage characteristics and signatures of a Berezinskii--Kosterlitz--Thouless transition, establishes the low-dimensional character of this superconducting state. Remarkably, the surface-associated superconductivity persists well beyond the bulk upper critical field, reaching a maximum ratio of Hc3/Hc2≈4.3, far exceeding the conventional Saint-James--de Gennes value of 1.695. These results demonstrate that Pb substitution can stabilize an anomalously enhanced low-dimensional superconducting state in NiBi3, providing a platform for investigating superconductivity at the boundary of a bulk superconductor.
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BibTeX
@misc{barik2026chemical,
title = {{Chemical Substitution as a Route to Anomalous Surface Superconductivity in NiBi$_3$}},
author = {Anupam Barik and Subhadip Chakrabarty and Achintya Low and Sudip Pal and Setti Thirupathaiah},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.33463},
eprint = {2610.33463},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.33463},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Chemical Substitution as a Route to Anomalous Surface Superconductivity in NiBi_3
AU - Anupam Barik
AU - Subhadip Chakrabarty
AU - Achintya Low
AU - Sudip Pal
AU - Setti Thirupathaiah
PY - 2026
DA - 2026/10/24
PB - arXiv
DO - 10.48550/arxiv.2610.33463
UR - https://arxiv.org/abs/2610.33463
AB - Stabilizing two-dimensional superconductivity in a bulk superconducting material provides a unique route to exploring the interplay between superconducting condensates of different dimensionalities. Here, we present evidence for a distinct surface-associated superconducting state in Pb-substituted NiBi_3. NiBi_2.8Pb_0.2 exhibits a resistive onset at T_c,onset^*≈8.1~K, nearly twice the bulk superconducting transition temperature of approximately 4.1~K. The absence of a corresponding Meissner response or specific-heat anomaly at the higher-temperature transition supports its non-bulk origin. A cusp-like angular dependence of the critical field, well described by the two-dimensional Tinkham model, together with nonlinear current--voltage characteristics and signatures of a Berezinskii--Kosterlitz--Thouless transition, establishes the low-dimensional character of this superconducting state. Remarkably, the surface-associated superconductivity persists well beyond the bulk upper critical field, reaching a maximum ratio of H_c3/H_c2≈4.3, far exceeding the conventional Saint-James--de Gennes value of 1.695. These results demonstrate that Pb substitution can stabilize an anomalously enhanced low-dimensional superconducting state in NiBi_3, providing a platform for investigating superconductivity at the boundary of a bulk superconductor.
ER -