NextFin news, On November 19, 2025, scientists from the Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) alongside the Cluster of Excellence ct.qmat announced a breakthrough finding in quantum materials physics. Their work, published in the prestigious journal Nature, documents the discovery of a novel topological nodal i-wave superconducting state on the surface of the topological Weyl semimetal platinum-bismuth-two (PtBi₂). This superconductivity manifests exclusively at the material’s two-dimensional top and bottom surfaces, leaving its interior metallic and non-superconducting. The research represents a major stride in uncovering intrinsic topological superconductors, which have eluded conclusive experimental verification until now.
The team, led by Dr. Sergey Borisenko and Prof. Jeroen van den Brink, used state-of-the-art angle-resolved photoemission spectroscopy (ARPES) with ultra-low photon energies (6 eV), enabling unprecedented resolution in momentum and energy space. They directly measured the superconducting gap on characteristic Fermi arcs—open surface electronic states unique to Weyl semimetals—finding a distinctive, anisotropic gap with nodes and six-fold rotational symmetry constraints. The superconducting order parameter exhibits i-wave symmetry (angular momentum l=6), a pairing state beyond the conventional s- and d-wave symmetries commonly observed.
This unconventional pairing generates six topologically protected Majorana cones on each surface. Majorana particles, long-sought quasi-particles which are their own antiparticles, have immense potential in creating error-resistant qubits for topological quantum computers. Their calculations demonstrated that these Majorana modes are localized not only on the surface but also form robust zero-energy hinge states at crystal step edges, providing controllable quantum degrees of freedom.
Despite the promising surface superconductivity, PtBi₂’s metallic bulk poses a significant challenge: bulk electronic states can interfere with the isolation needed for topological quasiparticles to function as fault-tolerant qubits. The researchers propose mitigation strategies such as fabricating ultrathin crystals to suppress bulk contributions or applying external magnetic fields to break time-reversal symmetry, thereby gapping unwanted bulk states and stabilizing chiral Majorana edge modes or localized zero modes at corners. Furthermore, engineering the phase difference of the superconducting order parameters between the two surfaces may allow realization of planar Josephson junctions within a monolithic crystal, opening avenues for intricate quantum devices.
From a materials science perspective, PtBi₂’s intrinsic topological superconductivity is rare, as most candidate materials have produced inconsistent or inconclusive empirical evidence. The discovery of a surface-only superconducting phase with i-wave pairing symmetry is likely driven by the interplay between strong spin–orbit coupling, crystalline symmetries (notably a threefold rotational symmetry), and the presence of multiple (12) Weyl cones that produce nontrivial Berry curvatures and Fermi arc surface states. Such conditions foster exotic quantum states inaccessible in conventional superconductors.
The impact on quantum technology is profound. Topological quantum computing exploits the non-abelian statistics of Majorana fermions to implement qubits inherently protected from decoherence and noise, tackling one of the biggest bottlenecks in quantum information science. PtBi₂’s surface-bound Majorana modes, with their topological protection and manipulability, indicate a viable material platform for scalable quantum computing architectures. Moreover, the nature of restricted electron pairing along six symmetrical surface directions, which reject pairing, points to novel pairing mechanisms potentially involving spin-momentum locking and Weyl physics—opening fertile ground for both experimental and theoretical exploration.
Looking forward, continued interdisciplinary efforts will be essential to overcome current obstacles. These include fabricating high-quality ultrathin PtBi₂ films, interface engineering to enhance isolation of surface states, and external controls (magnetic fields, gating) to fine-tune Majorana mode locations and lifetimes. The ability to directly observe and control hinge-localized Majorana modes represents a new frontier for quantum device integration. Additionally, breakthroughs in identifying or engineering bulk insulating analogs of PtBi₂ could lead to even more robust topological superconductors with minimal bulk interference.
In summary, the IFW Dresden and ct.qmat teams have revealed an extraordinary topological superconducting phase on PtBi₂’s surfaces, distinguished by its rare i-wave pairing and rich Majorana physics. This landmark discovery not only advances fundamental condensed matter physics but also propels materials closer to practical quantum computing applications—a promising harbinger for the future of fault-tolerant qubits and quantum hardware innovation.
According to the findings published in Nature and reported by EurekAlert!, the unique surface-only topological superconductivity in PtBi₂ is a pivotal step in the quest for intrinsic topological superconductors and stable Majorana quasiparticles, offering a concrete material pathway to scalable quantum computation. Researchers and quantum technology developers will keenly monitor subsequent experimental refinements and device realizations arising from this breakthrough.
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