Evolution of non-Kramers doublets in magnetic field in PrNi2Cd20 and PrPd2Cd20

Praseodymium-based 1-2-20 cage compounds PrT2X20 (T is generally Ti, V, Nb, Ru, Rh, Ir; and X is either Al, Zn, or Cd) provide yet another platform to study nontrivial electronic states of matter ranging from topological and magnetic orders to unconventional multipolar orders and superconductivity. In this paper, we report measurements of the electronic heat capacity in two Pr-based 1-2-20 materials: PrNi2Cd20 and PrPd2Cd20. We find that the lowest-energy multiplet of the Pr 4f2 valence configuration is a Γ3 non-Kramers doublet and the first excited triplet is assumed to be a magnetic Γ5. By analyzing the dependence of the energy splitting between the ground and first excited singlet states on an external magnetic field, we found that the maximum in the heat capacity corresponding to the Schottky anomaly in PrPd2Cd20, unlike PrNi2Cd20, shows a pronounced linear dependence on an external magnetic field at higher field values. This effect is associated with the exchange interactions between the field-induced magnetic dipole moments.