Jun 23, 2023
Cornell Researchers Visualize Electron Flow in Quantum Anomalous Hall Insulator
Cornell researchers have used magnetic imaging to directly visualize how electrons flow in a quantum anomalous Hall (QAH) insulator. Their findings challenge the long-held assumption that the
Cornell researchers have used magnetic imaging to directly visualize how electrons flow in a quantum anomalous Hall (QAH) insulator. Their findings challenge the long-held assumption that the transport current moves at the edges of the material, revealing that it actually occurs in the interior. This discovery provides new insights into the behavior of electrons in QAH insulators and resolves a longstanding debate about current flow in quantum Hall insulators more generally. The results will aid in the development of topological materials for next-generation quantum devices.
The researchers used a superconducting quantum interference device (SQUID) to scan a sample of chromium-doped bismuth antimony telluride, a known QAH insulator. The SQUID is an extremely sensitive magnetic field sensor that can operate at low temperatures. By imaging the current flows and reconstructing the current density, the researchers were able to observe the electrons flowing in the bulk of the material, contrary to previous assumptions.
The quantum Hall effect, first discovered in 1980, occurs when a magnetic field is applied to a specific material, causing it to become an insulator in the bulk while allowing an electrical current to flow in a single direction along the outer edge. QAH insulators achieve the same effect through magnetization. Understanding the intricacies of current flow in these materials is important for building more complex devices.
The researchers hope that their work will reopen the debate surrounding the understanding of topological materials and inspire further research in the field. They emphasize the importance of comprehending how current flows in order to fully understand the properties and potential applications of topological materials.