64 research outputs found
A Mechanism for Photoinduced Effects In Tetracyanoethylene-Based Organic Magnets
The photoinduced magnetism in manganese-tetracyanoethylene (Mn-TCNE)
molecule-based magnets is ascribed to charge-transfer excitations from
manganese to TCNE. Charge-transfer energies are calculated using Density
Functional Theory; photoinduced magnetization is described using a model
Hamiltonian based on a double-exchange mechanism. Photoexciting electrons from
the manganese core spin into the lowest unoccupied orbital of TCNE with photon
energies around 3 eV increases the magnetization through a reduction of the
canting angle of the manganese core spins for an average electron density on
TCNE less than one. When photoexciting with a smaller energy, divalent TCNE
molecules are formed. The delocalization of the excited electron causes a local
spin flip of a manganese core spin.Comment: 4 pages, 4 figure
Electronic structure and orbital polarization of LaNiO with a reduced coordination and under strain: first-principles study
First-principles density functional theory calculations have been performed
to understand the electronic structure and orbital polarization of LaNiO
with a reduced coordination and under strain. From the slab calculation to
simulate [001] surface, it is found that orbital occupation is
significantly enhanced relative to occupation owing to the
reduced coordination along the perpendicular direction to the sample plane.
Furthermore, the sign of the orbital polarization does not change under
external strain. The results are discussed in comparison to the bulk and
heterostructure cases, which sheds new light on the understanding of the
available experimental data.Comment: Phys. Rev. B (in press
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