Physicists at the Norwegian University of Science and Technology, led by Professor Jacob Linder at the QuSpin research center, report experimental evidence that may point to intrinsic triplet superconductivity in the alloy niobium rhenium, NbRe. The work, carried out in collaboration with experimental partners in Italy and published in Physical Review Letters, has drawn attention because triplet superconductors are widely regarded as a missing component in several quantum technology proposals.
Colangelo, F., Modestino, M., Avitabile, F., Galluzzi, A., Kakhaki, Z. M., Kumar, A., Linder, J., Polichetti, M., Attanasio, C., & Cirillo, C. (2025). Unveiling Intrinsic Triplet Superconductivity in Noncentrosymmetric NbRe through Inverse Spin-Valve Effects. Physical Review Letters, 135(22), 226002. https://doi.org/10.1103/q1nb-cvh6
Superconductors are materials that conduct electrical current without measurable resistance below a critical temperature. In conventional or singlet superconductors, electrons pair up in so called Cooper pairs with opposite spins. The total spin of the pair is zero. This configuration allows resistance free charge transport but does not directly support spin transport in the same way. Triplet superconductors differ in that the Cooper pairs carry a net spin. In practical terms, this means both charge and spin currents could, in principle, propagate without dissipation.
Professor Jacob Linder from Norwegian University of Science and Technology stated,
“Another advantage of this material is that it superconducts at a relatively high temperature, high temperature” is a little different than how we think of it.”
That distinction matters for spintronics and quantum computing. Spintronics relies on the spin degree of freedom of electrons rather than just their charge. In most existing devices, spin information decays quickly due to scattering and energy loss. A material that can carry spin without resistance would remove one of the central efficiency bottlenecks. As Linder has noted in several interviews, one of the main challenges in quantum technology is achieving sufficiently accurate and stable operations. Materials that combine superconductivity with robust spin transport could help address that limitation.
The reported findings are based on experiments using layered spin valve structures that incorporate NbRe between ferromagnetic layers. The team observed inverse spin valve effects that deviate from expectations for conventional singlet superconductivity. In simplified terms, the superconducting behavior appeared sensitive to the magnetic alignment of adjacent layers in a way that is consistent with equal spin triplet pairing. The authors argue that these signatures indicate intrinsic triplet superconductivity rather than a proximity induced effect.
Independent coverage from university and physics outlets has emphasized that such evidence must be treated cautiously. Triplet pairing has been claimed before in other materials, including certain heavy fermion systems and noncentrosymmetric superconductors, but definitive proof has often proven difficult. In this case, NbRe is a noncentrosymmetric alloy, meaning its crystal structure lacks inversion symmetry. That structural feature can allow mixed pairing states and makes triplet components theoretically plausible.
Another point highlighted in related reports is the operating temperature. NbRe becomes superconducting at around 7 kelvin. While still cryogenic, this is higher than some other candidate triplet systems that require temperatures near 1 kelvin. For experimental quantum devices, even a few kelvin difference can simplify cooling requirements and reduce system complexity. From an engineering perspective, this does not eliminate the need for cryogenic infrastructure, but it can influence cost and scalability considerations.
Triplet superconductivity is also of interest because of its connection to Majorana modes. In certain configurations, spin polarized Cooper pairs can give rise to quasiparticles that behave as their own antiparticles. These Majorana states are considered promising for topological quantum computing, where information is encoded in a way that is inherently protected from local disturbances. While the current study does not directly demonstrate Majorana particles, it provides a materials platform that could support such investigations.
The researchers themselves stress that further verification is required. Reproducibility by independent groups and additional spectroscopic tests will be necessary to establish whether NbRe is definitively an intrinsic triplet superconductor. Physical Review Letters selected the paper as a highlighted contribution, reflecting the broader interest in resolving this question.
For engineers working in quantum hardware, the implications are conditional but relevant. If a stable triplet superconductor can be integrated into device architectures, it could enable dissipation free spin currents and potentially improve coherence times in superconducting spintronic elements. It would also expand the design space for hybrid quantum systems that combine magnetic materials and superconductors.
Triplet superconductivity has been described for years as a target rather than a tool. The new results from NTNU and collaborators do not close the case, but they move the discussion from theoretical expectation toward experimental evidence in a material that can be fabricated and tested. Whether NbRe becomes a standard platform or simply a stepping stone, the study adds a practical data point to a field that has often relied more on models than measurements.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
