Hidden Kondo-Screening Revealed by Anomalous Hall Effect in Fe_3-δGeTe₂ Nanoflakes

The emergence of Kondo effect in Fe₃GeTe₂ (FGT) has attracted a lot of attentions due to a rare realization in 3d electron systems. However, the role of Fe-deficient on Kondo effect remains an open issue. Here, we focused on the studies of the anomalous Hall effect (AHE) for ideal stoichiometric and two different Fe-deficient FGT nanoflakes. Through the comparison of temperature dependence of spontaneous anomalous Hall resistance and coercive field among these FGT nanoflakes, unexpected reduction of anomalous Hall resistance and a kink behavior of coercive field below the Kondo crossover temperature in Fe-deficient samples well demonstrate the enhanced Kondo screening emerges due to Fe deficiency. Such an unconventional AHE could originate from the formation of enhanced local magnetism induced by the orbital-selective Mott correlation of Fe-I 3d electrons. This is consistent with the previous dynamical mean-field theoretical predictions, in which the distinct atomic environments of Fe-I and Fe -II give rise to dual role of local and itinerant magnetism respectively, thereby realizing the tuning of Kondo coupling through the change of electron filling. Our finding not only illustrate the role of Fe deficiency on the Kondo effect, but also provide a new insight to design the emergent quantum phenomenon.