= Ni, Pd) “cage” compounds*

Our group discovered a variation of the RT₂X₂₀ (R is a rare earth element, T a transition metal) “1-2-20” compounds with X = Cd. These “cage” compounds contain atomic cages within which R and T ions are located. The localized f- electron states of the R ions hybridize with the ligand states of the surrounding cage ions and generate correlated electron behavior. Pr-based “1-2-20” compounds with a Pr³⁺ non-Kramers doublet ground state in the crystalline electric field have been reported to exhibit quadrupolar Kondo phenomena, multipolar ordering, heavy fermion behavior, etc. In order to study the Fermi surface of PrT₂Cd₂₀ (T = Ni, Pd) compounds, we measured Shubnikov de Haas oscillations using the Proximity Detector Oscillator method for H up to 60 T at T = 1.5 K on single crystals.