Spin-singlet state of electrons in filled skutterudites Vyacheslav G. Storchak, Oleg E. Parfenov, Dmitry G. Eshchenko, Scott L. Stubbs, Roman Gumeniuk, Walter Schnelle, Rongwei Hu and Cedomir Petrovic EPL, 96 5 (2011) 57005 Published online: 22 November 2011 DOI: 10.1209/0295-5075/96/57005