Unusual behavior of the low-moment magnetic ground state of YbRh2Si2 under high pressure -: art. no. 180403

High-pressure investigations of the ground state properties of the non-Fermi-liquid system YbRh2Si2 (Yb-170-Mossbauer effect, electrical resistance and x-ray diffraction) reveal unusual features that are different from those found in Ce-related systems. We show that the ordered state with a low magnetic moment persists in a very large pressure range up to approximate to10 GPa and is associated with spin fluctuations. At 10 GPa the system undergoes a first-order magnetic phase transition to a high-moment state with mu(Yb)=1.9(1)mu(B) and magnetic ordering temperature T-m=7.5(4) K at 16.5 GPa. A magnetic phase diagram for YbRh2Si2 in the (p,T) space is suggested.