晶格常数的变化对FeNCN电子结构影响的第一性原理研究

First Principles Study on the Electronic Structure of FeNCN Influenced by the Change of Lattice Constant

采用第一性原理计算方法研究了c/a形变下FeNCN晶体的电子结构。结果表明在c/a形变下FeNCN晶体经历了半金属性到金属性的变化,当c/a不大于2.5时,FeNCN晶体表现为半金属性;当c/a大于2.5时,FeNCN晶体表现为金属性。Fe原子是晶体分子磁矩的最主要的贡献者,其自旋磁矩受c/a变化的影响程度较小。当FeNCN晶体表现为半金属性时,其分子磁矩能维持在稳定的整数值8.00μB;随着c/a的增加,分子磁矩逐渐减小。对c/a为2.3时FeNCN晶体电子结构的研究表明:此时自旋向上的子能带表现出间接带隙的半导体特征,晶体的半金属隙为0.11 eV。

The electronic structure of FeNCN with the change of c/a was studied by employing the first-principles method. The results show that the FeNCN undergoes a change from the semi-metallic character to metallic one with the change of c/a. The FeNCN presents semi-metallic character and metallic character when c/a≤2.5 and c/a〉25, respectively. The Fe atom is the major contributor to the total magnetic moment of FeNCN, whereas, the change of c/a has no obvious influence on the spin magnetic moment of Fe atom. The total magnetic moment can maintain the integral value of 8.00μB when FeNCN presents semi-metallic character, and the total magnetic moment will decreases when c/a increases. The investigations on the electronic structure of FeNCN with c/a=2.3 show that the spin-up states indicates an indirect band gap character and the semi-metallic gap of FeNCN is 0.11 eV.