Harvard Condensed Matter Theory Seminars

Piers Coleman, Rutgers University

Heavy Electron Quantum Criticality: signs of a new universality

Classical criticality, the discovery that matter develops universal behavior near a seond order phase transition, was the subject of a major paradigm shift in the understanding of statistical mechanics that took place some forty years ago. There is by now, a remarkable series of experiments on heavy electron materials that suggest that a new kind of universality may develop in the physical properties of quantum matter at a quantum phase transition.

Taking care to discuss the various efforts that have been made to save the quantum-spin density wave scenario, I shall discuss why we need to search for a new explanation. I will present our efforts to link quantum criticality in insulating quantum antiferromagnets, with quantum criticality in heavy electron systems, reviewing the possibility that the heavy electron Fermi liquid contains short-lived fractional virtual excitations that renormalize the Landau Parameters. In this scenario, the closure of the gap to fractional excitations at the quantum critical point appears to open the door to a radically new scenario about the way quantum fluctuations transform the metallic state at a quantum critical point.

E. Lebanon and P. Coleman, cond_mat/0610027.
J. Rech, P. Coleman,G. Zarand, O. Parcollet, Phys. Rev. Lett. 96, 016601, (2006).
P. Coleman, I. Paul and J. Rech, Phys. Rev. B 72, 094430 (2005).

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