Condensed Matter Seminars

Quantum criticality describes the strong fluctuations of a second order phase transition at zero temperature. There is growing evidence that it is relevant to a large part of the phase diagram of a variety of strongly correlated materials. In this talk, I will describe some of the basic issues that challenge the theoretical description of quantum criticality. I will go on to make the case for a new class of quantum critical point, with critical fluctuations that are genuinely quantum-mechanical. In the case of heavy fermion metals, the theory of local quantum criticality characterizes such quantum fluctuations in terms of the collapse of a Kondo entanglement scale. Finally, I will summarize some of the experimental evidences for this theory, particularly those concerning the evolution of the Fermi surface.