Researchers from Italy's Università degli Studi di Salerno, CNR-SPIN and the Norwegian University of Science and Technology (NTNU) recently found that the noncentrosymmetric superconductor niobium–rhenium (NbRe) could be the long-sought candidate for intrinsic spin-triplet pairing - a key ingredient for future superconducting spintronics and quantum computers.
Spin-triplet superconductors differ fundamentally from conventional “singlet” superconductors: their Cooper pairs carry spin as well as charge. This allows them to sustain spin-polarized supercurrents that can travel without resistance. Such a property would enable lossless spin transmission and stability in quantum information systems - a long-standing challenge in the field.
The researchers have now fabricated simple Py/NbRe/Py trilayers - where NbRe lies between two layers of permalloy (Py) and is capped with an antiferromagnetic layer - to probe these exotic correlations. Magnetic and electrical measurements revealed an inverse spin-valve effect, a response opposite to what conventional superconductivity predicts. This finding strongly hints at the presence of equal-spin-triplet Cooper pairs in NbRe.
What makes this result particularly compelling is the minimal nature of the device architecture. The absence of engineered magnetic textures or complex multilayers suggests that these triplet correlations arise intrinsically from the NbRe itself, rather than from interface-induced effects commonly engineered in hybrid superconducting–ferromagnetic systems.
Professor Jacob Linder of NTNU’s QuSpin Center notes that materials hosting triplet superconductivity could act as a “missing link” for scalable quantum information technologies.
Triplet superconductors can not only support dissipationless spin transport but may also enable the creation of exotic quasiparticles such as Majorana modes, which are considered promising building blocks for robust quantum computation.
NbRe combines several appealing traits: it is intrinsically noncentrosymmetric, compatible with thin-film fabrication, and exhibits superconductivity up to about 7 K - relatively high for a potential triplet system. These qualities make it a highly practical candidate for integration into spin-based superconducting circuits, quantum memory architectures, and energy-efficient logic.
While further experimental confirmation is required, the emerging picture places NbRe among the most promising intrinsic spin-triplet superconductor candidates to date - potentially marking a milestone in the ongoing search for functional quantum materials.