Evidence of mixed valence in (Eu1-xYbx)Ga4(Eu1-xYbx)Ga4 single crystals

In this paper we report on the magnetization and specific heat results on single crystals of the series (Eu,Yb)Ga4 aiming to study a possible valence change on both RE ions. The results show a decrease on TNTN and unit cell volume due to the chemical pressure. The enhancement of the effective moment suggests the presence of Yb3+Yb3+ while the constancy of the saturation magnetization points to a fixed 2+valence2+valence for Eu.