Magnetism and superfluidity of two-dimensional helium
The properties of atomically layered 3He and 4He films on the surface of graphite are being studied using heat capacity, continuous wave NMR and torsional oscillator techniques, to temperatures below 1mK. Two-dimensional 3He fluid monolayers provide a model system to understand correlated 2D Fermi liquids, while a solid 3He monolayer provides a model frustrated 2D magnet.
We are investigating submonolayer superfluidity of 4He and superfluidity of a 4He bilayer. In addition SQUID NMR instrumentation and methods are being developed and tested; and state-of-the-art instrumentation is now available for future experiments.
We have developed novel NMR spectrometers using broadband DC SQUID amplifiers. A broadband system suitable for low frequency NMR on two-dimensional solid 3He has been constructed and will be used to investigate its magnetic ground state. A highly sensitive tuned system operating at 1MHz has been built and tested on a low spin density sample (1017 spins on Mylar of surface area 0.1m2). This system will be used to study 3He films on such substrates of low specific surface area, and two-dimensional superfluidity in a thin 3He slab.
For further information contact Professor John Saunders.