Magnetic and structural phase transitions in CeCu_6-xAu_x

The heavy-fermion compound CeCu_6-xAu_x is a model system for unconventional quantum criticality. At small Au contents CeCu_6-xAu_x reveals a structural transition from an orthorhombic to a monoclinic crystal symmetry while at higher x an antiferromagnetic phase appears. To shed light on the interplay between quantum critical magnetic and structural fluctuations we performed neutron scattering experiments and thermodynamic measurements on samples with varying Au concentration between x = 0 and 0.3. The application of hydrostatic and chemical pressure allows to separate the magnetic from the structural transition and demonstrates that the unconventional quantum criticality is based on the magnetic fluctuations and not influenced by the monoclinic distortion.