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We report the growth of high-quality CeIrIn5 thin films with different crystal orientations on a MgF2 (001) substrate using pulsed laser deposition technique. X-ray diffraction analysis showed that the thin films were either mainly a-axis-oriented (TF1) or a combination of a- and c-axis-oriented (TF2). The characteristic features of heavy-fermion superconductors, i.e. Kondo coherence and superconductivity, were clearly observed, where the superconducting transition temperature (Tc) and Kondo coherence temperature (Tcoh) are 0.58 K and 41 K for TF1 and 0.52 K and 37 K for TF2, respectively. The temperature dependencies of the upper critical field (Hc2) of both thin films and the CeIrIn5 single crystal revealed a scaling behavior, indicating that the nature of unconventional superconductivity has not been changed in the thin film. The successful synthesis of CeIrIn5 thin films is expected to open a new avenue for novel quantum phases that may have been difficult to explore in the bulk crystalline samples.

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Ferromagnetic (FM) systems have attracted interest because a variety of novel phases can arise near a quantum critical point (QCP) where the FM order is suppressed to zero temperature. The Kondo lattice compound CePtAl 4 Si 2 is a candidate FM quantum critical material that becomes the FM state below T c = 3.7 K, but the possibility of the quantum criticality has yet to be studied. Here, we report a comprehensive temperature-pressure phase diagram of CePtAl 4 Si 2 using a systematic transport investigation. The FM compound CePtAl 4 Si 2 goes through three distinct ground states under pressure. In the low-pressure FM state, T c is gradually suppressed by pressure and a smooth extrapolation of T c (P) reaches zero temperature at a critical pressure of 7.0 GPa. However, the suppression of T c is interrupted by the appearance of another crossover temperature T * in the intermediate pressure range of 5.4-11.7 GPa, which shows a nonmonotonic pressure dependence. A fully coherent Kondo screened state is observed in the high-pressure regime. These results suggest that a FM QCP is avoided under pressure in the disordered Kondo system CePtAl 4 Si 2 .