高压下P4/mmm结构Fe_3Co晶态合金的磁性研究

Study on the Magnetism of P4/mmm Fe_3Co Crystalline Alloy at High Pressure

有序晶态合金Fe_3Co处于一种特殊的磁临界状态,这种磁临界状态下体系的磁性对压力极为敏感.基于密度泛函理论第一性原理的投影缀加平面波方法(PAW)研究P4/mmm结构晶态合金Fe_3Co的磁矩争电子结构随压力的变化规律.在压力为150 GPa附近出现了考虑电子自旋极化体系相对于不考虑电子自旋极化体系的相对焓差急剧下落后回升的现象,这与Fe2原子与Fe1原子对体系磁矩贡献发生变化的压力区间相对应,说明在150 GPa附近体系的微观磁结构对压力非常敏感,而且体系的基态结构处于不稳定状态.在压力大于700 GPa小于800 GPa区间内,体系的总磁矩线性显著减小,Fe_3Co晶态合金的铁磁性坍塌临界压力为850 GPa.

The ordered crystalline alloy Fe_3Co is a kind of special magnetic critical state,in which the magnetism of system is extremely sensitive to pressure.Using projector-augmented wave method based on density functional theory,we calculate the dependence of magnetic moment and electronic structure of crystalline alloy P4/mmm-Fe_3Co on external pressure.The enthalpy difference of system with electronic spin polarization being considered or not fluctuates dramatically near 150 GPa,which corresponds to the contribution of Fel and Fe2 atoms to the magnetic moment.It shows that the magnetic microstructure is extremely sensitive to pressure,as well as the ground-state structure is instable.When the pressure ranges from 700 GPa to 800 GPa,the total magnetic moment decreases linearly.The ferromagnetic collapse critical pressure of Fe_3Co crystalline alloy is 850 GPa.