Researchers at Tsinghua University, Southern University of Science and Technology and Boston College have directly observed charge stripes strengthening around magnetic vortex centers in an iron-based superconductor — and one of the two vortex states they mapped hosts a Majorana zero mode, a candidate building block for fault-tolerant quantum computing.

The paper, published in Physical Review Letters (DOI: 10.1103/6f1z-dvc6, October 2026), examines thin films of cobalt-doped barium iron arsenide, Ba(Fe₀.₉₄Co₀.₀₆)₂As₂, a type-II superconductor from the 122-type iron pnictide family. Cobalt atoms replace 6% of the iron sites in the crystal lattice, placing the films at optimal doping.

Why vortices matter

In type-II superconductors, magnetic fields penetrate the material through quantized vortices, each carrying a fixed amount of magnetic flux with circulating electrical currents around its core. Vortex cores act as natural traps for emergent electronic states, which is precisely what the team set out to probe.

"Our initial goal was to search for vortex bound states and possible Majorana zero modes in 122-type iron pnictides," senior author Can-Li Song told Phys.org. "Unexpectedly, we discovered charge stripes closely intertwined with different vortex states, which, with insights from our theoretical collaborators, became the central focus of this work."

A Majorana zero mode is a localized, zero-energy electronic excitation that behaves as a particle that is its own antiparticle. Because information spread across separated Majorana modes could survive some local disturbances, these states are attractive for quantum computing architectures that need protection from noise.

How the team mapped the stripes

First author Yu Liu said the group grew the optimally doped films by molecular beam epitaxy and studied them with low-temperature spectroscopic-imaging scanning tunneling microscopy, a technique that scans an atomically fine tip just above a surface to map electronic properties at different energies.

"By mapping the electronic states around many vortices with atomic-scale precision, we identified charge stripes and two distinct types of vortex states, including those hosting Majorana zero modes, and revealed their intimate spatial correlation," Liu explained.

The measurements produced three linked findings:

• Repeating charge stripes — periodic modulations of electronic charge along one direction — grow stronger around vortex centers.
• The vortices fall into two distinct types, classified by where their centers sit relative to the stripe pattern.
• One vortex type hosts a zero-energy state the researchers identify as a Majorana zero mode.

Topology, charge order and superconductivity in one vortex

Co-author Xu-Cun Ma called the co-localization the most striking result of the study. "The most exciting finding is that a Majorana zero mode, charge stripes, and a possible pair-density modulation all emerge within a single magnetic vortex and are intimately intertwined," he said. "This reveals how topology, charge order, and superconductivity can interact at the nanoscale."

The study establishes, for this specific material system, that electronic stripes and vortex-bound states are not independent phenomena but spatially correlated ones. Other groups can now test whether the same relationship appears in other type-II superconductors, a question the authors themselves raise.

For quantum computing research, the near-term significance is control. If charge order selects which vortex states form — and why one type binds a Majorana mode while the other does not — engineers gain a potential knob for positioning and stabilizing these modes rather than hunting for them statistically.

Song framed the open questions directly: "We would now like to understand why charge stripes select different types of vortices, how they couple to Majorana states, and whether this intertwined behavior is universal across iron-based superconductors. Ultimately, we hope to learn how these interactions can be used to control and manipulate Majorana zero modes."

The work grew out of a long-term effort to understand high-temperature superconductivity with atomic-scale precision, an approach the team argues is essential for separating genuine emergent states from artifacts in unconventional superconductors. Whether the stripe–vortex coupling generalizes across the iron-based family, and whether it can be engineered into usable Majorana devices, will define the next round of experiments.