Crystal field excitations to understand anisotropy behavior in new Ce based heavy fermions CeT4Al15 (T=Rh and Ir)

Recently we have synthesised new caged-type heavy fermion compounds CeT4Al15 (T=Rh and Ir) and investigated using bulk measurements. The low temperature susceptibility, heat capacity and resistivity measurements indicate that compound with T=Ir orders magnetically below 1.5 K, while that with T-Rh remains paramagnetic heavy fermion down to 0.3 K. Further high temperature susceptibility (T>100 K) confirms an easy c-axis, but below 100 K, there is a crossover to easy a-axis. Thus, it is interesting to investigate the crystal field excitations (i.e. single ion anisotropy) and their temperature dependence using inelastic neutron scattering study on these compounds to understand the crossover behaviour of the susceptibility. We therefore, propose to investigate the CEF excitations in CeT4Al15 (T=Rh and Ir) on MERLIN.