Quantum Criticality near Zero Temperature Phase Transitions – Meigan Aronson
Date: Mon. April 12th, 2004, 12:30 pm-1:30 pmLocation: Rockefeller 221
It is possible to drive magnetic ordering temperatures in certain metallic magnets to zero temperature by means of applied field, pressure, or compositional variation. We have been using neutron scattering measurements to study the development of dynamic and spatial correlations near one such T=0 antiferromagnetic transition in the heavy fermion system CeRu2Ge2, doped with Fe. We establish that the dynamical susceptibility is controlled equally by energy, absolute temperature, and wave vector magnitude, measured relative to the propagation wave vector of the parent finite temperature antiferromagnet. Unusually, critical slowing down affects a very broad range of wave vectors, suggesting that the quantum critical point is caused by the collapse of the moment magnitude, and not by a failure of moment-moment coupling.