Intriguing electron correlation effects in the photoionization of metallic quantum-dot nanorings |
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Authors: | I Baldea L S Cederbaum and J Schirmer |
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Institution: | 1.Theoretische Chemie, Physikalisch-Chemisches Institut, Universit?t Heidelberg,Heidelberg,Germany |
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Abstract: | We report detailed results on ionization in metallic quantum-dot (QD) nanorings described by the extended Hubbard model at
half filling obtained by exact numerical diagonalization. In spite of very strong electron correlations, the ionization spectra
are astonishingly scarce. We attribute this scarcity to a hidden quasi-symmetry, generalizing thereby similar results on optical
absorption recently reported Phys. Rev. B 75, 125323 (2007); 77, 165339 (2008)]. Numerical results indicate that this hidden quasi-symmetry of the extended Hubbard model does not evolve
into a true (hidden) symmetry but remains a quasi-symmetry in the case of the restricted Hubbard model as well. Based on the
observation on the number of significant ionization signals per each spatial symmetry, we claim the existence of a one-to-one
map between the relevant ionization signals of the correlated half-filled nanorings and the one-hole and two-hole-one-particle
processes possible in the noninteracting case. Similar to the case of optical absorption, numerous avoided crossings (anticrossings)
are present in the ionization spectra, which often involve more than two states. The present results demonstrate that ionization
could be a useful tool to study electron correlations in metallic QD-nanoarrays, providing information that is complementary
to optical absorption. |
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Keywords: | PACS" target="_blank">PACS 79 60 Jv Interfaces heterostructures nanostructures 78 67 Hc Quantum dots 71 10 Fd Lattice fermion models 71 27 +a Strongly correlated electron systems heavy fermions |
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