Unconventional metallic state in YbRh2Si2 - a high-pressure study

YbRh2Si2 is identified to be one of the few stoichiometric and the first Yb -based heavy fermion compound showing non-Fermi-liquid (NFL) effects at amb ient pressure. We present results of a detailed study of the electrical res istivity rho (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 < 1.5 GP a only one anomaly is observed in rho (T), two subsequent anomalies are fou nd at p > 1.5 GPa. These anomalies are interpreted as signature of (presuma bly 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. (C) 2001 Els evier Science B.V. All rights reserved.