Charge and crystal field electronic states in CeRh2Si2 and Ba2IrO4

Abstract

Abstract We point out the scientific importance of the increasing evidence for the existence of the discrete low-energy meV-energy states in compounds containing atoms with incomplete 4f, 5f, 3d shells and recently in iridates (5d shell). We point out that the realized charge state of the 3d/4f/5f/4d/5d atoms/ions in oxides is very close to the formal one obtained within the ionic model. In Ba2IrO4 the charge states are very close to Ba2+, Ir4+ and O2−. In CeRh2Si2, which is intermetallic and considered as a Kondo-lattice antiferromagnet, by detailed analysis of temperature dependence of the specific heat we have proved the realization of the trivalent charge state of practically all cerium ions. In the magnetic state, below TN of 36 K, the Kramers doublet becomes split and there appears a spin gap growing to 6 meV at T = 0 K.