Scientists Discover a New Quantum State of Matter Once Considered Impossible

An international team of researchers has identified a topological semimetal phase in the material CeRu4Sn6. The phase appeared at extremely low temperatures where physicists had thought such a state could not exist. The material reaches a point of quantum criticality under these conditions. When the material was chilled near absolute zero and an electric charge was applied, the electrons carrying current exhibited the Hall effect. The current bent sideways even though no magnetic field was present. This observation indicated that topological effects were shaping the path of the current through something inherent in the material. The topological effect proved strongest where the material was most unstable in its electron patterns. Quantum critical fluctuations stabilized the newly discovered phase. Physicist Qimiao Si from Rice University described the discovery as a fundamental step forward. Si said the work shows that powerful quantum effects can combine to create something entirely new. He added that the findings address a gap in condensed matter physics by showing strong electron interactions can give rise to topological states rather than destroy them. The new state has substantial practical significance, according to Si. Physicist Silke Bühler-Paschen from the Vienna University of Technology said the key insight demonstrated beyond doubt that the prevailing view must be revised. Researchers plan further work to see if the quantum state appears in other materials and to study the precise conditions required. The research has been published in Nature Physics.