Heavy fermion behavior in single crystal Pr_0.5Ir₄Sb_10.2Sn_1.8

Pr based filled skutterudites have proven to be immensely useful in understanding strongly correlated electrons and their interesting low temperature behavior. We have synthesized and measured single crystals of Pr_0.5Ir₄Sb_10.2Sn_1.8 [1], a compound based on Zintl electron counting rules. Investigations show heavy fermion behavior in the resistivity, specific heat, and magnetization, with a small superconducting fraction (<1%) also evidenced by resistivity and magnetization. Screening of 4f moments by conduction electrons is made apparent by a logarithmic upturn in the resistivity, the field dependence of the specific heat, and a careful analysis of the nuclear specific heat contribution. This material closely follows the Kadowaki-Woods ratio A/γ² ≈10^-5 μΩcm(K mol/mJ)². Magnetoresistance measurements show broad and kinked superconducting transitions that suggest multiple superconducting domains. We also discuss the possibility that the superconducting fraction is of reduced dimensionality or from an impurity phase.

[1] M. S. Cook and C. A. Burns, Physica B: Condensed Matter 598, 412428 (2020).