Magnetic Hysteresis of Molecular Faraday Effects of Phthalocyanine-Based Thin Films on Bi, Al-Substituted DyIG Substrates at Room Temperature and Demagnetization of the Ferrimagnetic Substrates by Photothermal Effects of Phthalocyanines

We report the switching of magneto-optical signals of a ferrimagnetic substrate by a selective laser irradiation of a phthalocyanine-based thin film on the substrate followed by application of an external magnetic field. We prepared thin films based on μ-oxo-bis[hydroxyl{2,9(or 10),16(or 17),23(or 24)-tetra-tert-buthylphthalocyanato}silicon], (SiPc)2, onto a ferrimagnetic rare earth garnet Bi0.8Dy2.2Fe4.3Al0.7O12 substrate, whose Curie temperature is appropriate for demagnetization by laser irradiation. The magnetic hysteresis of the magnetic circular dichroism (MCD) signals of (SiPc)2 was observed, which reflects the ferrimagnetic properties of the substrate. To the best of our knowledge, this is the first observation of the magnetic hysteresis of molecular Faraday effects at room temperature. After the selective pulsed laser excitation of (SiPc)2, the MCD intensity of the substrate decreased, which reflects the demagnetization of the substrate, and indicates that the photothermal energy produced in the ...