5-contributions to Fermi surfaces in (U,Th)RuSi

Haga, Yoshinori   

Electronic states of (U,Th)RuSi are studied experimentally to reveal the contribution of 5f electrons in URuSi which is extensively studied because of unusual properties. The reference compound ThRuSi without 5f electrons is well understood by the first principle calculations. However, the substitution of Th by small amount of U enhances the effective mass of the conduction carrier, leaving the Fermi surface volume unchanged. The behavior is significantly different from dilute magnetic alloys described by the Kondo effect.