Cross-over behavior of the localized to itinerant transition of 5f electrons in the antiferromagnetic Kondo lattice USb2

Abstract

In Uranium-based heavy fermion system, 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 USb2. Temperature-dependent dI/dV spectra from 4.7 K up to 140 K reveal several peak structures around the Fermi level. Two pronounced peaks are originated 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 is previously reported by another STM 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.

12 pages, 3 figures

References in corpus (6)

• Correlated Topological Insulators with Mixed Valence
• Imaging the Fano Lattice to 'Hidden Order' Transition in URu2Si2
• Visualizing heavy fermions emerging in a quantum critical Kondo lattice
• Additional energy scale in SmB${}_6$ at low temperature
• Dimerization induced by the RKKY interaction
• Microscopic mechanism for the unusual antiferromagnetic order and the pressure-induced transition to ferromagnetism in USb${}_2$