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arXiv · 2509.14590

Emergent Zeeman-Resilient Superconductivity Beyond the Spin-Paramagnetic Limit in Ultrathin NiBi3

Gabriel Sant'Ana·Leonardo Pessoa da Silva·Pedro Schio·David Möckli·Jan Aarts·Kaveh Lahabi·Milton A. Tumelero
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Abstract

The spin-paramagnetic limit sets a fundamental magnetic-field bound for conventional superconductors. Here we show that ultrathin NiBi$_3$ films develop a highly field-resilient superconducting state, with in-plane critical fields surpassing the spin-paramagnetic limit even above 0.9T$_C$. This enhancement is activated by dimensional confinement and depends sensitively on film thickness and morphology. Standard mechanisms, including strong spin-orbit coupling and multiband superconductivity, fail to quantitatively explain the observed robustness. These findings uncover an unconventional pathway for Zeeman-resistant superconductivity in low-dimensional materials beyond known Ising and Rashba scenarios, and further support earlier theoretical predictions of triplet pairing in low-dimensional NiBi$_3$.

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Gabriel Sant'Ana, Leonardo Pessoa da Silva, Pedro Schio, David Möckli, Jan Aarts, Kaveh Lahabi, Milton A. Tumelero. 2025-09-18. Emergent Zeeman-Resilient Superconductivity Beyond the Spin-Paramagnetic Limit in Ultrathin NiBi3. https://arxiv.org/abs/2509.14590

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