Crystalline electric fields and the ground state of YbRh2Si2 and YbIr2Si2

We have constructed the crystalline electric field (CEF) splitting of the energy levels of Yb3+ (4f13) in the clean intermetallic compounds YbRh2Si2 and YbIr2Si2. The data of measurements using methods of inelastic neutron scattering, electron spin resonance, and Mössbauer spectroscopy, together with relevant structural, thermodynamic, and magnetic properties, were used as input to calculations of the CEF level schemes in these non-Fermi-liquid systems. The experimental data of both compounds are found to be well explained on the basis of the CEF 4f-schemes with the Γt 6 - (1) ground state symmetry. © 2007 Elsevier B.V. All rights reserved