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A research team led by physicists Ming Yi and Emilia Morosan from Rice University has developed a new material with unique electronic properties that could enable more powerful and energy-efficient electronic devices.

The material, known as a Kramers nodal line metal, was produced by introducing a small amount of indium into a layered compound based on tantalum and sulfur. The addition of indium changes the symmetry of the crystal structure, and the result promotes the novel physical properties associated with the Kramers nodal line behavior. The research, in Nature Communications, represents a step toward low-energy-loss electronics and paves the way for more sustainable technologies.

"Our work provides a clear path for discovering and designing new quantum materials with desirable properties for future electronics," said Yi, associate professor of physics and astronomy.

Creating a new material

The researchers discovered that when they added tiny amounts of indium to tantalum disulfide (TaSâ‚‚), the material's underlying crystalline symmetry changed, leading to a uniquely protected pattern where electrons that spin up and spin down follow different pathways in momentum space, much like cars going in opposite directions on a highway. This happens until the two paths merge at the Kramers nodal line.

This new material also demonstrated the ability to carry electricity without energy loss, displaying superconducting properties. This dual characteristic could enable the development of topological superconductors, which may enhance power systems and computing technologies.

"Designing a material to meet the stringent symmetry conditions necessary for these special properties was challenging, but the outcomes have been rewarding," said Morosan, professor of physics and astronomy, electrical and computer engineering and chemistry and director of the Rice Center for Quantum Materials.

The team experimented with various compositions to observe the optimal properties. Using advanced tools such as spin-resolved angle-resolved photoemission spectroscopy and electrical transport in applied magnetic fields, they examined the tiny particles within the material. This technique allowed them to measure the energy, movement and spin of the electrons, the particles responsible for carrying electricity.

"Our experiments indicate that we can precisely adjust the material's properties to accentuate its topological traits, which is vital for future applications," said Yichen Zhang, a doctoral student at Rice and co-first author of the study.

The findings

To ensure the reliability of their findings, they combined the experimental observations with sophisticated first-principle theoretical calculations. The theoretical predictions aligned with the experimental data, providing deeper insights into the material's electronic topology.

By uncovering and tuning the properties of a Kramers nodal line metal, Yi and Morosan's team is not only expanding the understanding of quantum materials but also paving the way for transformative low-energy electronic technologies, said Junichiro Kono, director of the Smalley-Curl Institute and a co-author of the study.

"This groundbreaking work exemplifies the spirit of innovation that defines the Smalley-Curl Institute," Kono said. "It advances our mission to foster cross-disciplinary collaboration across many fields, bringing together physics, materials science and engineering to explore new quantum behaviors in matter."

The researchers say this discovery is just the beginning, and they are eager to continue exploring these new materials to uncover even more remarkable properties that could lead to breakthroughs in technology and science.

"There is still much to explore, and we are excited about the future possibilities that this new material presents," said Yuxiang Gao, a doctoral student at Rice and co-first author of the study.