Design and development of a low temperature, inductance based 3.5 MHz ac susceptometer.

We discuss the development of an induction based, low temperature high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K, in applied magnetic dc fields of up to 9 T. Careful balancing of the detection coils and calibration have allowed a sample magnetic moment resolution of 5x10^-10 Am² at 1 MHz. We will discuss the design and characterization of the susceptometer, and explain the calibration process and the applicabilty of the system to exisiting cryostat designs. We also include some example measurements on the spin ice materials, iron oxide based nanoparticles and superconductors to describe functionality to illustrate functionality.