Magnetic relaxation in single-crystal Co/Cu(100) superlattices

By measuring the relaxation of the magnetization in a fixed applied field for antiferromagnetic-coupled, single-crystal Co/Cu(100) superlattices, we show that the temperature dependence of the magnetic viscosity is markedly different for samples almost identical from the structural point of view. If the structure of the samples is properly characterized, deviations of the expected behavior for the temperature dependence of the magnetic viscosity can be uniquely interpreted. The results further indicate that care should be taken when assigning a temperature-independent behavior of the viscosity to quantum tunneling of the magnetization without additional experimental support.