We present results of high-resolution, low-temperature measurements of the Hall coefficient, thermopower, and specific heat on stoichiometric YbRh2Si2. They support earlier conclusions of an electronic (Kondo-breakdown) quantum critical point concurring with a field induced antiferromagnetic one. We also discuss the detachment of the two instabilities under chemical pressure. Volume compression/expansion (via substituting Rh by Co/Ir) results in a stabilization/weakening of magnetic order. Moderate Ir substitution leads to a non-Fermi-liquid phase, in which the magnetic moments are neither ordered nor screened by the Kondo effect. The so-derived zero-temperature global phase diagram promises future studies to explore the nature of the Kondo breakdown quantum critical point without any interfering magnetism.
@article{arxiv.1010.3441,
title = {Break up of heavy fermions at an antiferromagnetic instability},
author = {S. Friedemann and S. Wirth and S. Kirchner and Q. Si and S. Hartmann and C. Krellner and C. Geibel and T. Westerkamp and M. Brando and F. Steglich},
journal= {arXiv preprint arXiv:1010.3441},
year = {2015}
}