  Flat electronic bands are expected to show proportionally enhanced electron
correlations, which may generate a plethora of novel quantum phases and unusual
low-energy excitations. They are increasingly being pursued in
$d$-electron-based systems with crystalline lattices that feature destructive
electronic interference, where they are often topological. Such flat bands,
though, are generically located far away from the Fermi energy, which limits
their capacity to partake in the low-energy physics. Here we show that electron
correlations produce emergent flat bands that are pinned to the Fermi energy.
We demonstrate this effect within a Hubbard model, in the regime described by
Wannier orbitals where an effective Kondo description arises through
orbital-selective Mott correlations. Moreover, the correlation effect
cooperates with symmetry constraints to produce a topological Kondo semimetal.
Our results motivate a novel design principle for Weyl Kondo semimetals in a
new setting, viz. $d$-electron-based materials on suitable crystal lattices,
and uncover interconnections among seemingly disparate systems that may inspire
fresh understandings and realizations of correlated topological effects in
quantum materials and beyond.
