A precursor state to unconventional superconductivity in CeIrIn${}_5$

We present sensitive measurements of the Hall effect and magnetoresistance in CeIrIn${}_5$ down to temperatures of 50 mK and magnetic fields up to 15 T. The presence of a low temperature coherent Kondo state is established. Deviations from Kohler’s rule and a quadratic temperature dependence of the cotangent of the Hall angle are reminiscent of properties observed in the high temperature superconducting cuprates. The most striking observation pertains to the presence of a $\mathit{\text{precursor}}$ state–characterized by a change in the Hall mobility–that appears to precede the superconductivity in this material, in similarity to the pseudogap in the cuprate high $T_c$ superconductors.