The heavy-fermion compound CeCu6−xAux has become a model system for unconventional magnetic quantum criticality. For small Au concentrations 0≤x<0.16, the compound undergoes a structural transition from orthorhombic to monoclinic crystal symmetry at a temperature Ts with Ts→0 for x≈0.15. Antiferromagnetic order sets in close to x≈0.1. To shed light on the interplay between quantum critical magnetic and structural fluctuations we performed neutron-scattering and thermodynamic measurements on samples with 0≤x≤0.3. The resulting phase diagram shows that the antiferromagnetic and monoclinic phase coexist in a tiny Au concentration range between x≈0.1 and 0.15. The application of hydrostatic and chemical pressure allows to clearly separate the transitions from each other and to explore a possible effect of the structural transition on the magnetic quantum critical behavior. Our measurements demonstrate that at low temperatures the unconventional quantum criticality exclusively arises from magnetic fluctuations and is not affected by the monoclinic distortion.
@article{arxiv.1804.04513,
title = {Magnetic and structural quantum phase transitions in CeCu6-xAux are independent},
author = {K. Grube and L. Pintschovius and F. Weber and J. -P. Castellan and S. Zaum and S. Kuntz and P. Schweiss and O. Stockert and S. Bachus and Y. Shimura and V. Fritsch and H. v. Löhneysen},
journal= {arXiv preprint arXiv:1804.04513},
year = {2018}
}