Mn_3O_4纳米颗粒基于第一性原理的磁性研究

Mn_3O_4 Nanoparticles Magnetic Research Based on First Principles Study

采用低温热分解法合成了粒径为6nm的Mn3O4纳米粒子,XRD和SAED测试结果表明其为四方晶相,利用SQUID测试磁性发现在低温时,随着温度的升高,Mn3O4纳米粒子的矫顽力Hc和饱和磁化强度Ms逐渐减小,这主要是由颗粒磁有序性随着温度的升高遭到了破坏所导致的.通过基于第一性原理的理论计算,证明其磁性来源于Mn的d态电子,并且发现其电子态密度主要分布在费米面附近,由于颗粒的大小影响原子间距,从而造成电子态密度分布的不同,进而导致了不同粒径大小的Mn3O4纳米粒子的磁性的不同.

We were successfully synthesized the pure Mn3O4 nanoparticles at low temperature by thermal decomposition method,XRD and SAED exhibit samples as tetragonal crystal phase, the magnetic test found that the coercive force Hcand magnetic saturation Ms decrease with the increase of temperature, which may be attributed to magnetic disorder caused by thermal disturbance. The density of states （DOS） of Mn3O4 calculated by theoretical simulation proves that the magnetism derived from Mn-d elections, and the density of states distributed near the Fermi level. The particle size influence the atomic spacing, which further cause density of states is different, resulting in different magnetic properties.