Investigation of crystal field excitations in correlated 4f3 systems NdT2Zn20 (T = Co, Rh, and Ir)

Recently, rare-earth-based RT2X20 (T: transition metal, X = Al, Zn and Cd) compounds have attracted much attention because of the weak crystalline electric field (CEF) effect and the enhanced hybridization effect. In the present proposal, we focus on the compounds NdT2Zn20 (T = Co, Rh, and Ir) with magnetic Gamma 6 doublets of 4f3 configuration. They exhibit antiferromagnetic orders at TN = 0.53, 0.94, and 0.65 K, respectively, for T = Co, Rh, and Ir. The electrical resistivity shows upward curvature above TN and the magnetic entropy is reduced to (0.5)Rln2 at TN, probably resulting from enhanced c-f hybridization and/or magnetic frustration in the Gamma 6 doublet of the Nd ion. To understand the observed reduction of the magnetic entropy in NdT2Zn20 through investigating the CEF level schemes, we plan to perform inelastic neutron scattering experiments with powdered samples.