A Faraday magnetometer for studies of 3He films on Graphite

A Faraday-type magnetometer has been developed to measure the nuclear magnetization of monolayer 3He films adsorbed on Grafoil at temperatures down to 0.1 mK under high magnetic fields up to 10 T. The magnetic force is measured capacitively by monitoring the displacement of a wire-suspended copper plate, on which are diffusion-bonded many copper foils sandwiched by Grafoils. To eliminate a large background signal from Grafoil and copper, a double gradient coil system is employed to produce opposite field gradients at two regions the same distance apart from the center. At each region, exfoliated and non-exfoliated graphite foils are put one by one. Some other devices are discussed to improve a signal to noise ratio.