Study Of Magnetization Characteristics And Thermodynamic Properties On Multi-layer Nano-graphene

In recent years, graphene has received wide attention because of its unique structural characteristics, as well as the specific physical and chemical properties. It has been identified as a future star of the carbon-based materials. Nano-graphene has great potential applications in magnetics, electronics, sensing, energy storage, biomedicine, and so on. Therefore, study on the magnetization characteristics and thermodynamic properties on nano-graphene structure has very important significance. In this paper, we establishe the microscopic theoretical model of a bilayer and a trilayer nano-graphene with existence of exchange coupling, single-ion anisotropy and transverse field. Magnetization characteristics and thermodynamic properties of multi-layer nano-graphene structure on various physical parameters of magnetic nano-graphene have been studied in detail.Magnetization curves of the bilayer ferrimagnetic nano-graphene exhibit magnetization decrease with the increase of temperature when change physical parameters of the upper layer. Appear a new curve type in our study, which has a maximum in the magnetization curve at low temperatures then magnetization decreases rapidly when bJ and bD change. This phenomenon has been confirmed in the research of the dependence of magnetic susceptibility on various parameters. With the variation of exchange coupling, single-ion anisotropy and transverse field, magnetic susceptibility curves are both appear the regions which contain two peak points when bJ and bD change. In addition, the shapes of the blocking temperature curves are versatile. Blocking temperature increases with the increase of the absolute value of single-ion anisotropies aD(bD), and decreases with the increase of transverse fields a?(b?). Internal energy is rapidly increases as the temperature rises until it reaches a turning point and increases quickly after the turning point. The curve of specific heat also appears a typical characteristics of multi-peak phenomenon. Coercivity decreases with the decrease of bD and aJ, and increases with the decreases of a?. The competition of physical parameters resulting in metastable state occurs, hysteresis loops exhibit more than one loop.The shape of total magnetization of the trilayer nano-graphene system is great influenced by inner exchange coupling. Within certain parameters, magnetization curve also appears peak point. Especially, the region of magnetization convex becomes larger under the influence of interlayer exchange coupling aJ. Compared with the same structure of bilayer nano-graphene, the variations of blocking temperature, internal energy and specific heat are similar with the bilayer nano-graphene. Hysteresis loops also exhibit more than one loop.