Tuning the antiferromagnetic ground-state of Ce₂RhIn₈ by Ga-substitution

In heavy-fermion (HF) materials, unconventional superconductivity has been found in some compounds when the long-range magnetic order is suppressed by applied pressure and/or chemical doping. In this work, we explore the effect of Ga-substitution on the physical properties of single crystals of Ce₂RhIn₈ through measurements of temperature-dependent specific heat, magnetic susceptibility, and electrical resistivity. Our data show a monotonic decrease of the antiferromagnetic transition temperature from T_N = 2.8 K for the undoped compound to T_N = 2.1 K for the highest Ga-concentration achieved (x = 0.6) in the studied Ce₂RhIn_8-xGa_x crystals. Using a mean-field model with a tetragonal crystalline electric field (CEF) Hamiltonian and isotropic nearest neighbors magnetic exchange magnetic couplings to fit our data, we have evaluated how the Ce³⁺ CEF scheme and exchange interactions evolve as a function of Ga-doping. Our results show that the CEF scheme presented a systematic evolution as a function of Ga-concentration with changes in the Ce³⁺ CEF ground state wave function. We will discuss possible scenarios and future experiments in which these compounds may show a distinct evolution to a superconducting state when compared to pure Ce₂RhIn₈.