University of British Columbia physicist Dr. Meigan Aronson, alongside colleagues at the Stewart Blusson Quantum Matter Institute, has demonstrated a reversible method for switching the topological state of a quantum material. The work provides an experimentally verified route to toggling a material between a topological conductor and an insulator using mechanisms compatible with modern electronics. It is one of the clearest demonstrations to date of on-demand control of electronic topology in a single bulk crystal, a capability long predicted in theory but rarely realized in practice.
Bannies, J., Michiardi, M., Kung, H.-H., Godin, S., Simonson, J. W., Oudah, M., Zonno, M., Gorovikov, S., Zhdanovich, S., Elfimov, I. S., Damascelli, A., & Aronson, M. C. (2025). Electronic switching of topology in LaSbTe. Nature Materials. https://doi.org/10.1038/s41563-025-02396-3
The team focused on LaSbTe, a layered compound built from square-net arrangements of antimony and tellurium atoms. This material hosts what is known as a nodal loop — a closed contour in momentum space where electronic energy bands meet rather than separating. In this configuration the electrons can move with minimal scattering, forming a protected conduction channel. When the underlying lattice maintains a specific symmetry, called n-glide symmetry, this nodal loop remains intact and the material behaves like a high-mobility semimetal.
Dr. Meigan Aronso from University of British Columbia stated,
“Conventional electronics involve currents of electrons that waste energy and generate heat due to electrical resistance. Topological currents are protected by symmetry, and so they are promising for new types of electronics with significantly less dissipation.”
By tuning the ratio of antimony to tellurium, the researchers could deliberately distort the lattice and break this symmetry. Slightly increasing the antimony content caused the continuous nodal loop to collapse, opening a sizable energy gap and driving the system toward an insulating state. This composition-driven transition showed that the topological phase is tightly linked to the atomic arrangement rather than to external fields alone.
What makes the result more technologically relevant is that the transition can be reversed. On the crystal surface, the team applied a thin coating of potassium, which donates electrons and effectively restores the symmetry needed for the nodal loop. Once the symmetry is reinstated, the gap closes and the material returns to its metallic, topologically nontrivial state, re-enabling the dissipation-resistant current channel. Heating the sample then removes the potassium and brings the crystal back to its original configuration. According to first author Dr. Joern Bannies, repeated cycling confirmed the robustness of this switching process.
To track these changes directly, the researchers used angle-resolved photoemission spectroscopy. This technique measures electron energy and momentum, allowing the team to watch the electronic structure change as the nodal loop opened and closed. Complementary structural measurements using single-crystal X-ray diffraction verified that the changes arise from symmetry-breaking distortions in the crystal lattice itself. A minimal tight-binding model further supported the interpretation that the electronic topology is controlled by the lattice symmetry and electron count.
The ability to toggle topological states using methods familiar from semiconductor technology — chemical gating and slight compositional tuning — broadens the range of devices that could exploit topologically protected transport. Conventional electronics depend on resistive charge flow, which generates heat and limits efficiency. A material whose conduction properties can be switched through symmetry rather than through large voltages or magnetic fields could reduce energy losses and enable more compact, low-power architectures.
Several open questions remain, including long-term stability over many switching cycles, the feasibility of integrating such materials with existing chip-fabrication processes, and the performance limits at room temperature. Even so, this work provides a concrete demonstration that electronic topology can be engineered and reversibly controlled within a single bulk compound. It suggests the early stages of a technological pathway in which the geometry of electronic bands becomes a practical design variable, rather than a theoretical curiosity, for future electronic systems.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
