Insight into Kondo Screening in the Intermediate-Valence Compound SmOs4Sb12 Uncovered by Soft X-Ray Magnetic Circular Dichroism

Through a high-precision soft x-ray magnetic circular dichroism (XMCD) study of the intermediate-valence compound SmOs4Sb12, we show our successful approach of revealing unprecedented details of Kondo screening below a characteristic temperature of T-0 similar to 20 K in the paramagnetic phase. The multiplet XMCD structure at the Sm M-5 edge sensitive to the 4f configuration enabled us to observe a clear difference between the temperature evolution above and below T-0 with one- and two-component behavior, respectively. Our findings are in strong contrast to the conventional Kondo crossover that coincides with the valence transition, but are qualitatively accounted for by theoretical XMCD predictions combined with the two-fluid phenomenology recently proposed. This work contributes to the large context of Kondo physics that is closely related to quantum criticality in heavy fermion systems.