Unconventional metallic state in YbRh2Si2 — a high-pressure study

Abstract YbRh 2 Si 2 is identified to be one of the few stoichiometric and the first Yb-based heavy fermion compound showing non-Fermi-liquid (NFL) effects at ambient pressure. We present results of a detailed study of the electrical resistivity ρ ( T ) and the specific heat C ( T ) under hydrostatic pressure and map out the magnetic phase diagram up to about 2.5 GPa. While at p ρ ( T ), two subsequent anomalies are found at p >1.5 GPa. These anomalies are interpreted as signature of (presumably antiferro) magnetic phase transitions. The results of our specific heat measurements prove that those phase transitions are a true bulk effect. In addition, NFL-behavior is found to exist over a broad range of temperature and pressure for temperatures above the magnetic instability.