Description:

Title: Quantum Multi-criticality

Speaker: Professor Andrew Schofield, University of Birmingham

Abstract: Several quantum critical compounds have been argued to have instabilities towards both ferro- and antiferromagnet ic order. We present an analysis of a quantum multicritical point in an itinerant magnet with competition between ferro- and antiferromagnet ic order, using a modified Hertz-Millis theory. We are able to perform a one-loop renormalization group treatment of our action in the presence of multiple dynamic exponents. We conclude that in both two and three dimensions, when both quantum critical ferro- and antiferromagnet ic fluctuations are present in a system, the specific heat, thermal expansion and Grüneisen parameter obey the same laws as predicted for a ferromagnetic quantum critical point. The antiferromagnet ic correlation length and boundary of the ordered phase are suppressed by the dangerously irrelevant interactions with quantum critical ferromagnetic fluctuations. We find no difference between a quantum bicritical point and a quantum tetracritical point.

Keywords: Physics, Astronomy, CMP