A European team led by the University of Geneva (UNIGE) has empirically measured the ‘quantum metric’ within a topological insulator, a key advancement in understanding materials with unusual electrical conductivity. These topological insulators, first discovered in 2007, conduct electricity only on their surface, a phenomenon potentially valuable for future electronics and quantum computing. The quantum metric describes how electrons move across that surface. The experiment, conducted on a material composed of antimony and tellurium, confirms observations made on strontium titanate and lanthanum aluminate in previous work, suggesting the potential for electrical control of these quantum effects. “The entire scientific community now has a new property to explore in the materials of the future,” says Andrea Caviglia, full professor of Matter Physics at UNIGE, highlighting the significance of this breakthrough for technologies in development.
Quantum Metric Observation in Three-Dimensional Topological Insulators
A subtle warping of electron pathways has been directly observed in a three-dimensional topological insulator, marking a significant advance in understanding materials with the potential to improve electronics and quantum computing. This measurement, published in Nature Materials, confirms theoretical predictions and provides a new avenue for controlling the electrical properties of these promising materials. “Measuring it allows scientists to describe the geometric structure of the space in which the electrons move,” explains Giacomo Sala, senior research associate of Matter Physics (DQMP) at UNIGE and lead author of the study. The team’s success in observing this metric in a topological insulator consisting of antimony and tellurium expands the scope of known quantum material properties. This latest observation builds on earlier work led by Andrea Caviglia, full professor in the DQMP at UNIGE, who previously measured the quantum metric in strontium titanate and lanthanum aluminate. “These new results extend and confirm our previous observations, which were obtained using a very different material,” says Caviglia.
Strontium Titanate and Lanthanum Aluminate Measurements Confirm Theoretical Predictions
Measurements utilizing strontium titanate and lanthanum aluminate provided crucial empirical confirmation of theoretical predictions surrounding the quantum metric, until then, it had existed only in theory. The experiment was conducted on a quantum material composed of strontium titanate and lanthanum aluminate. Now, this team extends those findings to a three-dimensional topological insulator composed of antimony and tellurium, a metalloid extensively studied for its promising applications. This confirmation isn’t merely a replication of earlier work; the team demonstrated the effect in a fundamentally different material than the previous strontium titanate and lanthanum aluminate experiments, proving the quantum metric isn’t limited to specific compositions.
There are several families of topological insulators,” explains Giacomo Sala, senior research associate in the Department of Quantum Matter Physics (DQMP), Physics Section, UNIGE Faculty of Science and lead author of the study.
