In uranium-based heavy fermion systems, the $5f$ electrons display an intermediate character between partial localization and partial itinerancy, which makes the Kondo problem more complicated. Here we use scanning tunneling microscopy/spectroscopy to investigate the (001) surface of the Kondo lattice antiferromagnet ${\mathrm{USb}}_2$. Temperature-dependent $dI/dV$ spectra from 4.7 K up to 140 K reveal several peak structures around the Fermi level. Two pronounced peaks originate from the hybridization between the conduction and $5f$ electrons. We did not observe the mysteriously abrupt change of the electronic state at 45 K, which was previously reported by another scanning tunneling microscopy group and attributed to a novel first-order-like transition. Instead, we only observe continuous evolution of the $dI/dV$ spectra with temperature. Furthermore, in some scanning regions, we find significant Sb atoms missing from the top layer, which gives us the opportunity to investigate the electronic structure of the U-terminated surface. For the U-terminated surface, an additional sharp peak emerges, which is closely related to the magnetic order.

• Received 29 September 2021
• Accepted 15 November 2021

DOI:https://doi.org/10.1103/PhysRevB.104.235103