Updated: Oct 31, 2024

Jijo Malayil

Researchers are gaining new insights into magnetism and electronic interactions in advanced materials.

The findings of a team at Rice University could revolutionize fields like quantum computing and high-temperature superconductors.

Their study of iron-tin (FeSn) thin films change how scientists view kagome magnets, which are named after a traditional basket-weaving pattern. The team discovered that FeSn’s magnetic properties come from localized electrons, not the previously assumed mobile electrons.

According to the team, the findings challenge existing theories about kagome metals and offer new insights into magnetism, potentially guiding the creation of materials with customized properties for advanced technologies like quantum computing and superconductors.

“This work is expected to stimulate further experimental and theoretical studies on the emergent properties of quantum materials, deepening our understanding of these enigmatic materials and their potential real-world applications,” said Ming Yi, an associate professor of physics and astronomy and Rice Academy Senior Fellow, in a statement.

Exploring kagome magnetism

Kagome magnets, named after a traditional basket-weaving pattern, are materials featuring a distinct lattice-like structure. This design enables them to exhibit unique magnetic and electronic behaviors, which arise from the quantum destructive interference of electronic wave functions.

Studying the interplay of structure, electron interactions, and magnetism is made possible by magnetic kagome materials. Numerous magnetic kagome system types have been reported, such as the RMn6Sn6 family (where R is a rare earth element) and the binary FemXn family (where X is Sn or Ge).

Magnetic kagome materials are exciting for studying how magnetism, interactions, and structure work together. Many types of magnetic kagome systems have been discovered, such as the FemXn family (where X can be Sn or Ge) and the RMn6Sn6 family (with R being a rare earth element).

An image of a powerful quantum CPU on a PCB motherboard with data transfers.

In these materials, specific energy levels called kagome flat bands are close to a key energy level known as the Fermi level when they are not magnetically ordered. It is believed that partially filling these flat bands could lead to a type of magnetism called Stoner-type ferromagnetism.

However, scientists have not yet been able to observe the magnetic splitting that occurs at higher temperatures in these materials, leaving questions about how magnetism works in kagome magnets.

Advancing quantum technologies

In their new research, the team produced high-quality FeSn thin films and examined their electrical structure using a sophisticated method that combines molecular beam epitaxy and angle-resolved photoemission spectroscopy.

They discovered that the kagome flat bands stayed divided even at high temperatures, a sign that the material’s magnetism is driven by localized electrons. Understanding how electron behavior affects magnetic characteristics in kagome magnets is made more difficult by the electron correlation effect.

According to researchers, the work also provided a new understanding of how electron interactions affect the behavior of kagome magnets by revealing that certain electron orbitals had greater interactions than others, a process known as selective band renormalization that has been seen in iron-based superconductors.