Finding Chiral Superconductivity’s Fingerprint

April 23, 2026

With a carefully-designed experiment and a handful of tin atoms, UT’s physicists have found a long-sought form of superconductivity, taking one more step toward creating custom quantum materials.

Twists and Turns

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.

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.

The research team carefully deposited one-third layer of tin atoms on a silicon substrate, then used sophisticated imaging to pick up distinctive chiral superconductivity patterns.

Simply Beautiful Interference

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.

“Chirality is non-existent in high-temperature cuprate superconductors because they have a square lattice,” Weitering said, which gives you a different phase. “But in the tin layer, it exists because the lattice isn’t square. It’s a triangle.”

To see chiral superconductivity’s distinctive fingerprint he and his colleagues turned to quasiparticle interference imaging, or QPI.

“In condensed matter these particles always are moving in a surrounding that effects 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.”

The calling card for chirality is encoded in these patterns surrounding a point defect; a single atom defect to be precise.

“That could be a missing tin atom; it could a tin atom that has been replaced by a silicon atom because there’s a big reservoir of silicon underneath and sometimes atoms do that,” Weitering said. “You can never get a crystal perfect. There are always some defects in there. One crucial point in this system is that with the STM we can see each and every point defect in the tin layer.”

This research could serve as a template for using QPI to find other forms of unconventional superconductivity.

“Most superconductors are discovered through serendipity,” Weitering said. “This was all by design.”

Customizing materials is an important step on the long journey to possible applications.

“Quantum materials are usually not very useful unless you can make devices out of them,” he explained. “To make devices you usually need to make thin films and interfaces.”

He said that chiral superconductors are topological, and “people are excited about topological systems because we could use topological superconductors to build, for instance, qubits for quantum computing.”

Qubits store or process information that’s highly sensitive to outside influences like temperature, everyday radiation, etc.

“Topological systems are interesting in a sense that topological property is not something that’s local,” Weitering said. “It’s global. By making it global it’s much less sensitive to perturbations.”

Showing Off for Friends

Though the tin-silicon system was designed with intention, recognizing the chirality pattern actually did involve a little bit of serendipity.

Weitering’s former postdoctoral research associate, Fangfei Ming, is now a professor in China. He sent QPI images of the material taken by his group, showing how the detail has improved over time—specifically patterns that resemble flowers.

Weitering was impressed and showed the results to Assistant Professor Ruixing Zhang.

“Ruixing looked at this pattern and saw something very striking that was at the center of the page,” he said.

Zhang went back to his office and had his graduate students (Zhuo Chen and Yuchang Cai) do some numerical and analytical calculations, proving that only chiral superconductivity will result in the flower-like QPI pattern with an atomic-size hole at the center—chiral fingerprints.

“Ruixing saw that and his intuition was right,” Weitering said, admitting that, at first, he was more focused on the sharpness of the images when he shared them with Zhang.

“I was just showing off,” he joked.

Having friends to work with (and impress) is a critical element to moving fundamental research forward.

“If you do science by yourself, you’re never going to get there,” Weitering said.

He, Zhang, Johnston, Chen, and Cai all contributed to the PRX research, along with colleagues from China. He and Zhang are also reviewing patterns from QPI images and plan to create a database. They hope to train a machine learning program to recognize the intricate details of those patterns.

“It’s really part of the MRSEC (the university’s Materials Research Science and Engineering Center, funded by the National Science Foundation),” Weitering said. “It’s using AI to analyze data. It’s curating data. You need to train AI with data. It’s not just theory; it’s also experimental data. Then there’s the validation component of theory predictions.”

Verifying where the theory leads next is a big part of his work. First there was the Nature Physics research; now the PRX findings.

“We found superconductivity,” Weitering said. “Then we found chiral superconductivity. Every time we get a step further.”

Hanno Weitering Named 2026 Macebearer

April 8, 2026

Chancellor’s Professor and Professor of Physics Hanno Weitering is the University of Tennessee, Knoxville, 2026 Macebearer. The honor is the highest bestowed on UT faculty members and recognizes outstanding service to the university, its students, and the greater society.

Keeping with tradition, the new Macebearer was surprised by an entourage, this year comprising Vice Chancellor for Research Deb Crawford, College of Arts and Sciences (CAS) Divisional Dean Kate Jones and Associate Dean Todd Moore, and Weitering’s wife Carol, who had been following his location on her phone to make sure he made it to the physics colloquium in time for the announcement.

Weitering said he was running a bit late and didn’t think much of the texts and calls checking that he was on his way.

“Then the deans and the vice chancellor suddenly came in with Carol, which felt completely bizarre,” he said. “Everything happened very quickly.”

As Professor and Head Adrian Del Maestro shared later in a departmental message: “For those of you who joined us for Colloquium today, you witnessed a truly surprised Hanno accepting the award from Vice Chancellor Crawford! Congratulations to a member of our faculty who truly embodies the volunteer spirit!”

Robert Hinde, Executive Dean and Herbert Family Dean’s Chair for the College of Arts and Sciences, added praise for Weitering’s selection.

“Hanno’s record of teaching, research, and service, combined with his personal dedication to the physics and university community, make him an ideal choice for Macebearer,” said Hinde.

On what being Macebearer means to him, Weitering said he “can only reflect with deep gratitude on the tremendous support I’ve had throughout my career. I’m fortunate to be part of a strong physics department with wonderful colleagues, and to have benefited from the guidance and support of mentors, colleagues, and department heads. As head, I had the privilege of serving under an inspirational dean during a period of significant progress for the university. It gave me the opportunity to give back by helping position the department for new challenges and opportunities. Now, I’m glad to be back focused on teaching and research—being an academic truly is a privilege.”

Small Systems with Big Potential

Weitering joined the university in 1993 as part of the physics department’s condensed matter research program. His work explores materials at the microscopic level, focusing on their structure and the behavior of conduction electrons, particularly at surfaces and interfaces. By scattering small numbers of tin atoms across a silicon substrate, he has created idealized material systems that revealed a novel form of superconductivity—the long-sought chiral superconducting state.

While many superconductors have historically been discovered through serendipity, Weitering takes a deliberate, theory-driven approach. Because theoretical models often simplify the complex physics of real materials, he creates precisely engineered material systems that faithfully represent those models. These nanoscale realizations allow him to directly test and validate their predictions. Each step in uncovering the subtle physics of these atomic-scale designs brings researchers closer to identifying and controlling phases with potential applications in quantum technologies.

Weitering has published more than 100 original research papers that have been cited nearly 7,800 times, and was recognized by the College of Arts and Sciences with the 2023 Distinguished Research Career Award.

A True Volunteer Family

Weitering’s contributions to the university go far beyond atomic creativity. In 2012 he began a decade of leadership as head of the physics department, a position that for several years overlapped with a 10-year position as deputy director of UT’s Joint Institute for Advanced Materials (JIAM) (now the Institute for Advanced Materials and Manufacturing, or IAMM). Among his proudest accomplishments is the number of scientists involved in quantum science who joined the university during that time (including Del Maestro). He has also supervised or co-supervised 15 PhD students (including four new PhD alumni in the past four years) and 13 postdocs. He’s taught courses including Thermal Physics, Structure of Matter, and Introduction to Quantum Mechanics, as well as a capstone course for physics majors. He and Carol are also parents of two UT CAS alumni: Bart, who graduated in 2013 with a double major in geological sciences and physics; and Hanneke, who graduated in 2014 with a physics degree.

Carrying the Mace, and a Legacy

Weitering earned both master’s and doctoral degrees in chemistry at the University of Groningen in his native Netherlands. He moved to physics when he accepted a Benjamin Franklin Postdoctoral Fellowship at the University of Pennsylvania. From there he joined the UT faculty. The Macebearer is one of many honors he’s won during his tenure. In addition to selection as a Chancellor’s Professor and the CAS Distinguished Research Career Award, he has been recognized with the JIAM Chair of Excellence, election as a Fellow of the American Physical Society, and election as a Fellow of the American Association for the Advancement of Science.

Weitering will be formally recognized as Macebearer at the Chancellor’s Honors Banquet later this month. He will carry the symbolic mace during the spring 2026 commencement ceremonies, following in the footsteps of former physics professors chosen for the honor: the late Bill Bugg, Lee Riedinger, and Soren Sorensen.