Photomagnetic Effects in Mn-Porphyrin Based Molecular Magnet

The photo-induced magnetic properties of [MnR4TPP] [TCNE], (TPP=tetraphenylporphyriyn, TCNE=tetracyanoethylene, R=OC12H25) charge transfer molecular magnet were investigated. Results of AC susceptibility and DC magnetization as well as relaxation measurements were obtained. The substance under study, composed of pseudo 1D chains, forms a long range ordered 3D magnetic system at Tc=22 K. Magnetic moments of MnIII (S=2) and those located at TCNE− anions are coupled antiferromagnetically in the chain. At temperatures above ∼8 K the interchain interaction favors the ferromagnetic orientation of the resulting chain moments, while at lower temperatures the coupling is negative and at the initial magnetization curve the spin flop transition is observed. The magnetization of the sample as a function of the applied field is strongly influenced by the illumination with light of different wavelength. Both the value of magnetization and the time dependence of magnetization changed during the irradiation. On the other hand, the AC susceptibility results show no significant change upon irradiation.