Low Temperature Group

T: 01784 44 3486
F: 01784 47 2794
E: j.saunders@rhul.ac.uk

CV
Professional activities

My main current interest is the experimental investigation of helium, particularly low dimensional helium, as a “quantum simulator” to investigate fundamental problems in condensed matter physics and quantum matter. We study both fermionic systems (3He) and bosonic systems (4He).

Studies of liquid 3He, in its normal and superfluid phases, were crucial to the development of Landau Fermi liquid theory (the “standard model” of interacting electrons) and theories of unconventional superconductivity. In the same way we believe that the investigation of low dimensional helium will underpin attempts to understand more complex and technologically important materials. A major current interest is the investigation of quantum phase transitions and quantum criticality in helium films.

A key interest of mine is to develop new experimental techniques to address these problems. Most recently the primary foci have been: the use of SQUIDs to take NMR into new regimes of sensitivity and the new domain of micro-tesla fields; the marriage of nano-fabrication techniques with ultra-low temperature physics.

The research is undertaken on two nuclear adiabatic demagnetization refrigerators in our Low Temperature Laboratory.

The main topics we are experimentally modelling with helium are: Mott-Hubbard transitions; vacancy doped Mott insulators; search for two dimensional supersolids; frustrated two-dimensional magnetism; heavy fermion behaviour and quantum criticality in 3He bilayers; Luttinger liquids; mesoscopic transport in helium films; new p-wave superfluid states of matter in 3He films.

In addition I collaborate with Prof Brian Cowan on spinodal decomposition, homogeneous nucleation and supersolidity in bulk solid helium.

The SQUID NMR techniques are being exported into the study of biological systems, in our new Biodiagnostics Laboratory. I collaborate in this activity, which is led by Casey and Lusher.

Although virtually all of our research is conducted in-house, we work successfully with several international collaborators.

Key publications

1. Bilayer 3He; a simple two dimensional heavy fermion system with quantum criticality
M Neumann, J Nyéki, B Cowan and J Saunders
Science 317, 1356 (2007)

See also Perspective in same issue.

2. Evidence for a Mott-Hubbard transition in a two dimensional 3He fluid monolayer.
A Casey, H Patel, J Nyéki, B P Cowan and J Saunders.
Phys. Rev. Lett. 90, 115301 (2003).

3. Ferromagnetism of 2D solid 3He investigated by SQUID NMR.
A Casey, R Schanen, C P Lusher, B P Cowan and J Saunders.
J. Low Temp. Phys. 134, 649 (2004).

4. Interfacial friction of thin 3He slabs in the Knudsen limit.
A Casey, J Parpia, R Schanen, B Cowan and J Saunders. Phys. Rev. Lett 92, 255301 (2004).

5. Studies of sub-micron 3He slabs using a high precision torsional oscillator.
Antonio Corcoles, Andrew Casey, Jeevak Parpia, Roger Bowley, Brian Cowan and John Saunders
AIP conference proceedings 850, 99-100 (2006) http://link.aip.org/link/?APCPCS/850/99/1

5. A nuclear magnetic resonance spectrometer for operation around 1 MHz with a sub-10 mK noise temperature, based on a two-stage dc superconducting quantum interference device sensor, L. V. Levitin, R. G. Bennett, A. Casey, B. P. Cowan, C. P. Lusher, J. Saunders, D. Drung, and Th. Schurig, Appl. Phys. Lett. 91, 262507 (2007)