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Abstract:
The change of intermolecular spin exchange interaction within a half-filled band of two-dimensional Langmuir films formed by photoresponsive radicals has been investigated theoretically. The photoswitching of magnetic properties arises as a result of a reversible photochemical reaction within the building units of the Langmuir films. These units consist of a photochromic moiety connected with a polymethine radical. The various contributions to the Heisenberg effective exchange integral, the direct (Coulomb), kinetic, and indirect spin exchange, have been calculated using the band theory of organic open-shell pi- electron systems.