Piers Coleman

I am fascinated by the possibility that quantum criticality 
represents a fundamentally new kind of universality for phase 
transitions.  Were it true, it would mean the "end of the line"
for Landau Ginzburg Theory - which, since the advent of
Weiss Theory, has provided us with the work horse for understanding
phase transitions and criticality. 

Here are my current interests in the area of Quantum Critical Points.

(1) Construction of a controlled mean field theory for 
antiferromagnetism and the heavy electron state of the Kondo lattice.
Such a mean field theory would link the Kondo paramagnet with the local
moment antiferromagnet, providing clues as to the mysterious zero modes
that drive the quantum phase transition and its unusual transport properties.

(2) Possibility of fundamentally new classes of critical theory.
One fascinating possibility, concerns the wide class of new
supersymmetric stat mech models in dimensions higher than two - 
which Scott Thomas will talk about at our conference.

(3) Possibility of superconducting quantum critical points.  Several heavy
electron superconductors, CeCoIn_5, UBe_13, CeCu_2Si_2 and most probably,
PuGaIn_5,appear to either be hiding an antiferromagnetic phase transition
beneath their supeconducting veil.  In CeCoIn_5, this qcp appears to located
very close to the upper critical field. Could this be a superconducting
quantum critical point? Normal BCS theory does not accomodate this
possibility, but we know that heavy electron superconductors have order
parameters which may combine the spin of the local moments and the conduction
electrons.  Could it be that when this order parameter falls apart, one has a
superconducting quantum critical point?

(4) Novel kinds of order.  Orbital antiferromagnetism and its possibility in
URu2Si2? Composite pairing in heavy electron superconductors.

(5) Transport properties at a quantum critical point. Is there a common origin
    to the T-linear resistivity and T^2 Hall angle of heavy electron quantum
    critical points and the cuprates at optimal doping?













(1) What is the right mean-field description for the emergence
of antiferromagnetism in a heavy electron system? For a large class
of heavy electron systems, it is clear that the quantum spin density
wave picture

Presumeably, 
once we have the correct mean-field theory, then the novel
modes, and the critical theory will  become clear.