Hyperfine Interactions in CeT2Ge2 (T = Mn, Co) Heavy Fermions Compounds Measured by TDPAC

Time Differential Perturbed γ-γ Angular Correlation (TDPAC) technique was used to measure the magnetic hyperfine field at both Ge and Ce sites in CeMn2Ge2 and CeCo2Ge2 intermetallic compounds. The 111In (111Cd) probe nuclei was used to investigate the hyperfine interaction at Ge sites, while the 140La (140Ce) nuclei was used to measure the magnetic hyperfine field at Ce site. The present measurements cover the temperature ranges from 10-460 K for CeMn2Ge2 and 9-295 K for CeCo2Ge2, respectively. The result for 111Cd probe showed two distinct electric quadrupole frequencies above magnetic transition temperatures, in both compounds and a combined interaction in the magnetic region. The temperature dependence of the magnetic hyperfine field at 111Cd at Mn site for the CeMn2Ge2 compound showed a transition from ferromagnetic to antiferromagnetic phase around 320 K and from antiferromagnetic to paramagnetic phase at 420 K. While a small magnetic field was measured on 111Cd at Co site, no magnetic field on 140Ce site was observed in CeCo2Ge2.