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Quantum anomalous Hall effect
The SI realization of the ohm is based on the quantum Hall effect, which requires a magnetic field of several Tesla. This large magnetic field limits the ohm’s deployability and renders it incompatible with the superconducting-based voltage standard. The recently realized quantum anomalous Hall effect yields a quantized resistance without a magnetic field. This opens the possibility of a unified, deployable electrical standards system, consisting of the superconducting volt integrated with a quantum anomalous Hall resistor in a single cryostat. Combining the volt and ohm through a quantum Ohm’s law would represent a realization of the ampere, bringing all base electrical units into a single system.
The primary impediment to this unified, deployable electrical standards system is the mK temperatures needed for an accurately quantized quantum anomalous Hall resistance. These low temperatures require expensive and unwieldy dilution refrigerators. Our work is focused on increasing the operating temperatures of quantum anomalous Hall materials to 1 to 2 K. We study magnetically doped topological insulators, and newly realized 2-d materials, such as rhombohedral graphene-based systems and twisted MoTe2 homobilayers. We utilize a combination of scanning probe and transport measurements, together with theory, to uncover and remedy the limiting factors in the quantum anomalous Hall effect.
Description
The QAHE project has two thrusts, click on the links below to learn more about each one.
THE TEAM
