Photoinduced magnetism caused by charge-transfer excitations in tetracyanoethylene-based organic magnets |
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Authors: | Erdin Serkan van Veenendaal Michel |
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Institution: | Department of Physics, Northern Illinois University, DeKalb, Illinois 60115, USA. |
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Abstract: | The photoinduced magnetism in Mn-tetracyanoethylene (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 spins into the lowest unoccupied orbital of TCNE with photon energies around 3 eV increase 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. |
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