Measuring Hall Conductivity Using a Cantilever Torque Magnetometer

We present measurements of Hall conductivity of a Corbino-disc patterned thin film sample fabricated on a cantilever-based torque magnetometer. Applying a voltage difference across the disc creates a magnetic dipole moment propotional to σ_xy. This dipole moment interacts with an applied magnetic field, exerting a torque on the cantilever. Such a technique uses symmetry to eliminate the longitudinal resistance dependence which spoils measurements of σ_xy in insulators at low temperaure. We have fabricated high-Q cantilevers with Corbino-disks and tested the minimum detectible σ_xy both at room temperature and when cooling. Our preliminary results indicate that this technique could be used to accurately probe σ_xy in previously inaccessible materials.