Effects Of Sizes On Magnetic Properties Of Magnetic Nanomaterials

Recently,nano-magnetic materials have been widely used in science and technology.A great deal of research has been done in experimentally and theoretically.Nano-magnetic materials are different from those of their bulk materials.The properties of nano-magnetic materials are related to their sizes.As the size of magnetic nanomaterials decreases,the specific surface area of system increases.It results in significant changes in physical and chemical properties.In particular,nanoparticles of different sizes exhibit many properties.They have great potential application,such as targeted drug delivery,biosensor and high density magnetic recording.Therefore,it is of great significance to study the magnetic and other physical properties of nanoparticles and nanoclusters.A center decorated tetragonal nanoparticles is developed to describe by mixed spin 3/2 and 2 Ising model with anisotropy.Within the effective-field theory with correlations,the magnetic properties of the system have been studied in applied transverse magnetic field.The effects of the exchange coupling,the anisotropies and the transverse magnetic field on the phase diagram,magnetization and magnetic susceptibility are investigated for three sizes.Some interesting features have been obtained,such as the reentrant phenomenon and the depressed saturation magnetization in certain range of parameters.The comparison of magnetic properties with three sizes proves that size has an important effect on them.The study of center decorated nanoparticles for different size described by mixed spin Ising model may open a new field of magnetism in two-dimensional nanomaterials.Based on mixed spin-3/2 and spin-2 Ising model,the magnetic properties of different sizes of decorative nanoclusters are studied.The magnetization,susceptibility and phase diagrams have been obtained for different size nanoclusters.By comparison,the surface decoration size of the clusters is large,the corresponding phase transition temperature is also biger for the same parameters.The the exchange coupling,anisotropic crystal field and transverse field have important effects on the magnetic properties of the nanoclusters.