Princeton scientists discover exotic quantum state of matter

Below right: These images collected by Princeton University scientists show (top) the first direct image of the dancing pattern of electrons on the edge of the bismuth-antimony bulk crystal, which is a quantum Hall insulator; (center) a schematic and another image showing the electron distribution in three dimensions; and (bottom) a schematic and an image conveying the distribution of edge-electrons in two dimensions. Images: Zahid Hasan -   - 'Quantum Hall-like effect' found in a bulk material without an applied magnetic field A team of scientists from Princeton University has found that one of the most intriguing  phenomena in condensed-matter physics - known as the quantum Hall effect - can occur in nature in a way that no one has ever before seen. Writing in the April 24 issue of Nature, the scientists report that they have recorded this exotic behavior of electrons in a bulk crystal of bismuth-antimony without any external magnetic field being present. The work, while significant in a fundamental way, also could lead to advances in new kinds of fast quantum or "spintronic" computing devices, of potential use in future electronic technologies, the authors said.   - "We had the right tool and the right set of ideas," said Zahid Hasan , an assistant professor of physics who led the research and propelled X-ray photons at the surface of the crystal to find the effect. The team used a high-energy, accelerator-based technique called "synchrotron photo-electron spectroscopy." And, Hasan added, "We had the right material." The quantum Hall effect has only been seen previously in atomically thin layers of semiconductors in the presence of a very high applied magnetic field.