Effect of Ge-doping and pressure in the vicinity of the QCP of YbRh2Si2

Abstract We present electrical resistivity ( ρ ) and AC magnetic susceptibility measurements on Ge-doped single crystals of the NFL compound YbRh 2 Si 2 . Upon producing the volume expansion (Δ V ≃+0.3%) necessary to tune this material to its QCP, the low-temperature ρ ( T ) data of YbRh 2 (Si 0.95 Ge 0.05 ) 2 are found to follow ρ ( T )= ρ 0 + bT over three decades in temperature. We compare the effect of Δ V to that produced by the application of hydrostatic pressure, and show that the linear temperature dependence is intrinsic to the proximity to the QCP and not due to disorder induced by Ge-alloying.