Separation of Energy Scales in Undoped YbRh2Si2 Under Hydrostatic Pressure

The temperature–magnetic field ( T – H ) phase diagram of YbRh 2 Si 2 in the vicinity of its quantum critical point is investigated by low- T magnetization measurements. Our analysis reveals that the energy scale \(T^{\star}(H)\), previously related to the Kondo breakdown and terminating at 0.06 T for T →0, remains unchanged under pressure, whereas the antiferromagnetic critical field increases from 0.06 T ( P =0) to 0.29 T ( P =1.28 GPa), resulting in a crossing of T N ( H ) and \(T^{\star}(H)\). Our results are very similar to those on Yb(Rh 1- x Co x ) 2 Si 2 , proving that the Co-induced disorder can not be the reason for the detachment of both scales under chemical pressure.