Note: nonlinear susceptibility from high DC field torque magnetometry

Torque magnetometry is a convenient technique to measure the magnetic properties of anisotropic materials. Advances in micromachining have made torque magnetometers precise and reliable even in adverse conditions such as very high magnetic fields and very low temperatures. In most applications with such magnetometers the measured torque signals are used to arrive at the linear magnetic susceptibility. In this short note we extend torque magnetometry to measure nonlinear susceptibilities and illustrate our methods with representative data on the heavy fermion compound UPt3.