  Replacing a magnetic atom by a spinless atom in a heavy fermion compound
generates a quantum state often referred to as a 'Kondo-hole'. No experimental
imaging has been achieved of the atomic-scale electronic structure of a
Kondo-hole, or of their destructive impact (Lawrence JM, et al. (1996) Kondo
hole behavior in Ce0. 97La0. 03Pd3. Phys Rev B 53:12559-12562; Bauer ED, et al.
(2011) Electronic inhomogeneity in a Kondo lattice. Proc Natl Acad Sci.
108:6857-6861) on the hybridization process between conduction and localized
electrons which generates the heavy fermion state. Here we report visualization
of the electronic structure at Kondo-holes created by substituting spinless
Thorium atoms for magnetic Uranium atoms in the heavy-fermion system URu2Si2.
At each Thorium atom, an electronic bound state is observed. Moreover,
surrounding each Thorium atom we find the unusual modulations of hybridization
strength recently predicted to occur at Kondo-holes (Figgins J, Morr DK (2011)
Defects in heavy-fermion materials: unveiling strong correlations in real
space. Phys Rev Lett 107:066401). Then, by introducing the 'hybridization
gapmap' technique to heavy fermion studies, we discover intense nanoscale
heterogeneity of hybridization due to a combination of the randomness of
Kondo-hole sites and the long-range nature of the hybridization oscillations.
These observations provide direct insight into both the microscopic processes
of heavy-fermion forming hybridization and the macroscopic effects of
Kondo-hole doping.
