192 research outputs found
Ab initio Evidence for Strong Correlation Associated with Mott Proximity in Iron-based Superconductors
We predict that iron-based superconductors discovered near d6 configuration
(5 Fe 3d orbitals filled by 6 electrons) is located on the foot of an
unexpectedly large dome of correlated electron matter centered at the Mott
insulator at d5 (namely, half filling). This is based on the many-variable
variational Monte-Carlo results for ab initio low-energy models derived by the
downfolding. The d5 Mott proximity extends to subsequent emergence of
incoherent metals, orbital differentiations due to the Mott physics and
Hund's-rule coupling, followed by antiferromagnetic quantum criticality, in
quantitative accordance with available experiments.Comment: 9 pages, 5 figure
Ab initio derivation of electronic low-energy models for C60 and aromatic compounds
We present a systematic study for understanding the relation between
electronic correlation and superconductivity in C60 and aromatic compounds. We
derived, from first principles, extended Hubbard models for twelve compounds;
fcc K3C60, Rb3C60, Cs3C60 (with three different lattice constants), A15 Cs3C60
(with four different lattice constants), doped solid picene, coronene, and
phenanthrene. We show that these compounds are strongly correlated and have a
similar energy scale of the bandwidth and interaction parameters. However, they
have a different trend in the relation between the strength of electronic
correlation and superconducting transition temperature; while the C60 compounds
have a positive correlation, the aromatic compounds exhibit negative
correlation.Comment: 13 pages, 7 figures, 7 table
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