Details of Grant 

EPSRC Reference:	GR/J85349/01
Title:	APPLICATION OF RENORMALIZATION GROUP TECHNIQUES TO MODELS OF HEAVY FERMIONS AND KONDO INSULATORS
Principal Investigator:	Chen, Professor Y
Other Investigators:	Hewson, Dr AC
Researcher Co-Investigators:
Project Partners:
Department:	Mathematics
Organisation:	Imperial College London
Scheme:	Standard Research (Pre-FEC)
Starts:	28 September 1994	Ends:	27 September 1997	Value (£):	117,233
EPSRC Research Topic Classifications:	Condensed Matter Physics
EPSRC Industrial Sector Classifications:
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Summary on Grant Application Form
Two significant new approaches have been developed recently for strong correlation models of high Tc superconductors and heavy fermions. One is based on the fact that, for high dimensionality, lattice models with on site interactions can be mapped into self-consistent impurity problems. The solution of the lattice model then requires a way of accurately calculating the dynamical response of the effective impurity model. This is a difficult problem which we were able to solve in earlier work by extending the numerical renormalisation group technique. We obtained accurate predictions for impurity dynamics including the temperature dependence. We now propose to build upon this work, incorporating the self-consistency requirement to make predictions for the lattice models of heavy fermions.The other approach is that of the renormalised perturbation theory which we have developed here recently. The perturbation theory is reorganised as in a renormalisable field theory so that we have a low temperature expansion about a Fermi liquid fixed point. The impurity models to second order give the exact low temperature results. For lattice models to lower order it gives a renormalised band theory. We propose to look at the next order terms for lattice models, that take account of quasi-particle interactions, and to investigate the stability of the fixed point against magnetic and superconducting instabilities.
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Organisation Website:	http://www.imperial.ac.uk