Electrical Resistivity and Magnetoresistance in Monodispersed Oxide-Coated Fe Cluster Assemblies

摘要: We systematically studied electrical resistivity and magnetoresistance (MR) of size-monodispersed oxide-coated Fe cluster assemblies with the mean sizes d = 9–17 nm prepared by a plasma-gas-condensation-type beam deposition system. The strongly depend on temperature, surface oxidization degree clusters (namely O2 gas flow ratio RO2), size d, magnetic field. exhibit large negative MR effect which is further enhanced at low temperatures due to dominant contribution spin-dependent tunneling process between cores through oxide shell layers. It has been found that field dependence all shows no saturation tendency up maximum H 50 kOe completely disagrees magnetization curves indicate tendency. These results have interpreted consideration state Fe-oxide layers, mechanism, intercluster correlation. high-field nonsaturation behavior in attributed spin-disordered structure, frozen spin-glass-like temperatures, crystallites or whole thinner