Fingerprints of super spin-glass state in two-dimensional nanoscopic system

Novel two-dimensional magnetic assembly was designed, manufactured, and its static and dynamic magnetic response was investigated. The assembly contains Fe3O4 nanoparticles of nominal size 7 nm which were deposited on plasma-treated polypropylene substrate using a grafting technique. The nanoparticles create ag-glomerates with size distribution ranging nominally from 10 nm to 110 nm. The temperature dependence of zero -field and field-cooled susceptibility is consistent with glassy behavior. The relative shift of maximum in alter-nating susceptibility & UGamma; & AP;0.075 and z & upsilon; = 10 obtained from critical slowing down analysis also support the formation of the collective states akin to super spin-glass. However, the absence of collapse in dynamic scaling of alternating susceptibility data using predictions for three-dimensional spin-glass with Gaussian distribution of magnetic coupling and two-dimensional bimodal spin-glass suggests that the studied system is not representative of the used limiting models. The investigation of memory effects revealed the coexistence of relaxation phe-nomena of collective degrees of freedom and individual nanoparticles. The obtained results suggest that the studied assembly is appropriate for the investigation of super spin-glass state in two-dimensional magnetic system with dominant dipolar interaction.