Superferromagnetic domain state of a discontinuous metal insulator multilayer

Polarized neutron reflectivity (PNR) and magnetometry studies have been performed on the granular multilayer [Co80 Fe20 (1.3 nm)/Al2 O3 (3 nm)] 10. Due to strong interparticle interactions, a collective superferromagnetic state is encountered. Cole-Cole plots drawn from the complex ac susceptibility are measured as functions of frequency, temperature, and field amplitudes that hint at the relaxation, creep, sliding, and switching regimes of pinned domain walls that are in close agreement with results obtained from simulations. Very slow switching with exponential relaxation under near-coercive fields is confirmed by PNR measurements. The complete absence of spin-flip scattering confirms that the magnetization reversal is achieved merely by domain nucleation and growth.