Electron Spin Resonance of Disordered Sm Ions in SmB₆

Abstract

Electron spin resonance (ESR) of disordered Sm ion located at the B₆-cluster site in SmB₆ is observed. Various valence states such as Sm³⁺, Sm²⁺, Sm⁰, Sm⁻ and Sm²⁻ are found. It becomes clear that there are two ways of electron trapping on the disorder site. One of them is the 4f-trap where additional electrons occupy the vacant 4f-level of the disordered Sm with the Hund rule. On the other hand, weakly coupled donor electrons exist in addition to the 4f level electrons. Two possibilities of the coupling model are discussed.