Atomic-scale studies of correlated Kondo physics in epitaxial FeSb₂ thin films

The search for correlated topological states in d-electron systems has motivated investigations of FeSb₂, a candidate topological Kondo insulator. Although bulk FeSb₂ exhibits low-temperature resistivity saturation reminiscent of f-electron systems such as SmB₆, direct atomic-scale evidence of its surface states and Kondo signatures has been lacking. Here, we report the synthesis of high-quality FeSb₂ films on SrTiO₃(001) via molecular beam epitaxy. Topographic STM images reveal atomically flat terraces with elongated islands and rectangular pits, consistent with the (101) orientation identified by X-ray diffraction. Tunneling spectroscopy shows a pronounced resonance near the Fermi level, well-described by a combined Fano and Lorentzian line shapes. These results indicate FeSb₂ thin films as a promising d-electron platform for exploring topological Kondo physics.