"A flower-like pattern exposes chiral superconductivity's long-sought fingerprint"
"Scientists have known about superconductivity for more than a century. At low temperatures, resistance in certain materials vanishes and they carry electrical current without losing any energy. Superconductors are part of particle accelerators and magnetic resonance imaging machines. While they need extremely cool environments to work, the mechanism that drives them is quite well understood: electrons, which normally repel each other, form pairs and carry the current.
("The center of each image (a) and (b) shows a substitutional silicon defect. The pronounced dark spot at the center of panels (a) and (c), indicated by blue arrows, is a key signature of a chiral superconducting order parameter. The top two panels are experimental data; the lower two panels are theoretical simulations. Credit: Physical Review X (2026). DOI: 10.1103/jmmf-mpr8")
Chiral superconductivity is another story. Here, electron pairs reject the typical symmetry and twist into a signature left or right "handedness." Scientists have searched for this phase for decades because it has promise for quantum technologies.
In 2023, Chancellor's Professor Hanno Weitering and Bains Professor Steve Johnston published findings in Nature Physics reporting that strategically scattering tin atoms across a silicon base could give rise to a superconductor. They proposed the system could also be a potential chiral superconductor. This latest work, outlined in Physical Review X, provides the evidence."
("Fourier transformed QPI images for bias voltages of (a) −1.3, (b) −0.8, (c) −0.5, (d) +1.3, (e) +0.8, and (f) +0.5 meV, as indicated in each panel. These images correspond to the dI/dV maps in Fig. 2. The 2kF wave vector and G11 reciprocal lattice vector are indicated in panel (c). ΓK¯ is shown in panel (f). For a detailed explanation of these momentum space images, (...) Credit: Physical Review X (2026)")
"Weitering said the structural and electronic simplicity of the tin-silicon material is the key to seeing chirality. More complex materials have overlapping states and multiple interactions that can mask the telltale patterns.
In this system, one-third layer of tin means a controlled deposition of atoms placed relatively far apart on a silicon layer. Those atoms spontaneously organize into a nicely ordered triangular lattice. The geometry is important."
"To see chiral superconductivity's distinctive fingerprint, he and his colleagues turned to quasiparticle interference imaging, or QPI.
"In condensed matter, these particles are always moving in a surrounding that affects their behavior, so they're not really a single entity anymore," Weitering said. "They're all under the influence of their surroundings. That's why we call them quasiparticles."
If you picture electrons behaving like waves, he explained, and think about throwing stones in a pond, one after another in different spots, you'll see waves start to run into each other.
"We call those interference patterns," he said. "This is where the interference comes from: quasiparticle interference. With the scanning tunneling microscope (STM) we can see those waves. Quasiparticles interfere and give these beautiful patterns.""
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