441 research outputs found
Molecular Kondo effect in flat-band lattices
The Kondo effect of a single magnetic impurity embedded in the Lieb lattice
is studied by the numerical renormalization group. When the band flatness is
present in the local density of states, it quenches the participation of all
dispersive electrons in the Kondo singlet formation, and reduces the many-body
Kondo problem to a two-electron molecular Kondo problem. The two-electron
analog of the many-body Kondo singlet, a quantum entanglement of two spins, is
stable at low temperature, and the impurity contributions to thermodynamical
and dynamical quantities are qualitatively different from that obtained in the
conventional Kondo effect in systems without flat bands. The existence
conditions of the molecular Kondo effect in narrow band systems are also
discussed
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