University of Toronto

Physics Department

Abstract

Heavy fermion alloys offer the opportunity to study a quantum phase transition from a magnetic ordered into a disordered groundstate tuned by 'chemical' or real pressure. The example CeCu_6-xAu_x will be considered with a critical concentration x_c=0.1, where the ordering temperature vanishes. Especially neutron scattering data are discussed, which successfully revealed the magnetic fluctuation spectrum. For the first time quantum critical fluctuation including energy/temperature scaling are observed in a heavy fermion alloy close to an antiferromagnetic quantum critical point. But the data at x_c also show that the fluctuation spectrum is not mean-field like. The observed unusual dynamic and reduced correlation dimension suggest a special scenario in this compound, which also offers an explanation for the observed non-Fermi-liquid properties, which could not be understood assuming 'conventional' fluctuations.

Contact: Prof. James R. Drummond (416-978-4723)

Dr. Schröder is a candidate for the position in the Physics department

See http://www.physics.utoronto.ca/~qocmp