Huge residual resistivity in the quantum critical region of CeAgSb2

We have studied the effect of pressure on the electrical resistivity of a high-quality single crystal CeAgSb2 which has a small net ferromagnetic moment of 0.4μB/Ce. The magnetic ordering temperature Tord = 9.7 K decreases with increasing pressure p and disappears at a critical pressure pc ≃ 3.3 GPa. The residual resistivity, which is close to zero up to 3 GPa, increases steeply above 3 GPa, reaching 55μΩ cm at pc. A huge residual resistivity is found to appear when the magnetic order disappears.