Zero-bias anomaly in ferromagnetic Ni nanoconstrictions

Abstract

We study the electrical conductance in a ferromagnetic Ni constriction, changing its size using a mechanically controllable break junction technique. A Fano resonance with a zero-bias anomaly, likely due to the Kondo effect, appears in Ni atomic-scale contacts and changes shape as the size of the contact changes. Moreover, the zero-bias anomaly persists in large size constrictions with nearly 50-atom configurations where the bulk ferromagnetic properties should be retained, despite the decrease of the signal intensity. The results suggest that the Kondo effect and ferromagnetism could coexist in the ferromagnetic nanoconstrictions.