Ce2Ir3Ga5 : A new locally noncentrosymmetric heavy fermion system

Abstract

Recently, a new type of unconventional superconductivity with a field-induced transition between two different superconducting (SC) states was discovered in the heavy fermion system ${\mathrm{CeRh}}_2{\mathrm{As}}_2$. This unusual SC state was proposed to be based on specific symmetries of the underlying structure, i.e., a globally centrosymmetric layered structure, but where the Ce layers themselves lack inversion symmetry. This new type of SC state has attracted strong interest, prompting the search for further heavy fermion systems crystallizing in structures with appropriate symmetries. We report the discovery and the study of a new Ce-based heavy fermion system with a globally centrosymmetric structure but without inversion symmetry on the Ce-site, ${\mathrm{Ce}}_2{\mathrm{Ir}}_3{\mathrm{Ga}}_5$. A single crystal x-ray diffraction study revealed an orthorhombic ${\mathrm{U}}_2{\mathrm{Co}}_3{\mathrm{Si}}_5$ type structure. Resistivity, specific heat, and magnetization measurements indicate a moderate-heavy fermion behavior with a Kondo energy scale of the order of 40 K. Most experimental results suggest the absence of magnetic order, but a tiny anomaly in the specific heat opens the possibility for a very weak, itinerant type of ordering.