Spontaneous magnetization-induced phonons stability in γ′-Fe4N crystalline alloys and high-pressure new phase
Spontaneous magnetization-induced phonons stability in γ′-Fe4N crystalline alloys and high-pressure new phase
复制标题
γ-Fe4N 晶体合金和高压新相中自发磁化引起的声子稳定性
DOI：
10.1016/j.jmmm.2017.09.086
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发表时间：
2017
影响因子：
2.7
通讯作者：
Lin Li
中科院分区：
文献类型：
--
作者：
Tai-min Cheng;Guo-liang Yu;Yong Su;Lin Zhu;Lin Li
采用基于密度泛函理论的第一性原理计算方法研究了有序c0-Fe4N晶体合金在高压下的晶格动力学稳定性和磁性。动力。在高压下，通过传导软化现象，发现了稳定的新相P2/m-Fe4N。利用软模相变理论研究了c0-Fe4N中声子在10 GPa处的M点（0.5 0.5 0）。与不考虑电子自旋极化的c0-Fe4N声子谱相比，。在低于1 GPa的压力下，自发磁化诱导了铁磁相c0-Fe4N的基态晶格动力学稳定性。而P2/m-Fe4N的热力学稳定性更好。在低于1 GPa的压力下，两相的磁矩几乎相同。在2.9 ~ 19 GPa的压力范围内，P2/m相的基态结构比c0相更稳定。在20 ~ 214 GPa的压力范围内，两相的磁矩几乎相同，但c0相的基态结构比P2/m相的基态结构更稳定。压力范围为143.8 - 214 GPa。相反，P2/m相的基态结构为。当压力在214 GPa以上时更稳定。在214到300 GPa的压力范围内，磁性。P2/m相的磁矩小于c0相的磁矩，两相磁矩趋于一致。压力超过300gpa时保持一致。
The stability of lattice dynamics and the magnetism of the ordered c0-Fe4N crystalline alloy at high pressures were studied by first-principle calculations based on density-functional theory. The dynamical.stable new phase P2/m-Fe4N at high pressures was found by conducting the softening phenomenon at.the point M (0.5 0.5 0) of the acoustic phonon at 10 GPa in the c0-Fe4N via soft-mode phase transition.theory. Compared to the phonon spectrum of c0-Fe4N without considering electronic spin polarization,.the ground-state lattice dynamical stability of the ferromagnetic phase c0-Fe4N is induced by the spontaneous magnetization at pressures below 1 GPa. However, P2/m-Fe4N is more thermodynamically stable.than c0-phase at pressures below 1 GPa, and the magnetic moments of the two phases are almost the.same. The ground-state structure of P2/m phase is more stable than that of c0-phase in the pressure range.from 2.9 to 19 GPa. The magnetic moments of the two phases are almost the same in the pressure range.from 20 to 214 GPa, but the ground-state structure of c0-phase is more stable than that of P2/m phase in.the pressure range from 143.8 to 214 GPa. On the contrary, the ground-state structure of P2/m phase is.more stable when the pressure is above 214 GPa. In the pressure range from 214 to 300 GPa, the magnetic.moment of P2/m phase is lower than that of c0-phase, and the magnetic moments of the two phase tend.to be consistent when the pressure exceeds 300 GPa.