Intermediate-valence state of the Sm and Eu in SmB6 and EuCu2Si2: neutron spectroscopy data and analysis

P S Savchenkov; P A Alekseev; A Podlesnyak; A I Kolesnikov; K S Nemkovski

doi:10.1088/1361-648X/aaa1aa

Intermediate-valence state of the Sm and Eu in SmB₆ and EuCu₂Si₂: neutron spectroscopy data and analysis

J Phys Condens Matter. 2018 Feb 7;30(5):055801. doi: 10.1088/1361-648X/aaa1aa.

Authors

P S Savchenkov¹, P A Alekseev, A Podlesnyak, A I Kolesnikov, K S Nemkovski

Affiliation

¹ National Research Nuclear University MEPhI, 115409, Moscow, Russia. National Research Centre Kurchatov Institute, 123182, Moscow, Russia.

PMID: 29324435
DOI: 10.1088/1361-648X/aaa1aa

Abstract

Magnetic neutron scattering data for Sm (SmB₆, Sm(Y)S) and Eu (EuCu₂Si_2-x Ge _x ) intermediate-valence compounds have been analysed in terms of a generalized model of the intermediate-radius exciton. Special attention is paid to the correlation between the average ion's valence and parameters of the low-energy excitation in the neutron spectra, such as the resonance mode, including its magnetic form factor. Along with specific features of the formation of the intermediate-valence state for Sm and Eu ions, common physical mechanisms have been revealed for systems based on these elements from the middle of the rare-earth series. A consistent description of the existing experimental data has been obtained by using the concept of a loosely bound hole for the Eu f-electron shell in the intermediate-valence state, in analogy with the previously established loosely bound electron model for the Sm ion.