The effect of pressure and Ir substitution in YbRh2Si2

In this paper we present a study of the electrical resistivity of Yb(Rh1-xIrx)(2)Si-2, x = 0.06, under high pressure and in a magnetic field. Ir substitution expands the unit cell and leads to a suppression of the antiferromagnetic transition temperature to zero, where eventually a quantum-critical point (QCP) exists. We applied hydrostatic pressure to reverse the effect of substitution. Our results indicate that Yb(Rh0.94Ir0.06)(2)Si-2 is situated in the immediate proximity of a volume controlled QCP, but still on the magnetically ordered side of the phase diagram. The temperature-pressure phase diagram of Yb(Rh0.94Ir0.06)(2)Si-2 resembles that of the pure compound. Substitution acts mainly as chemical pressure. Disorder introduced by substitution has only minor effects.