物理学报Issue(14)：1-11,11.DOI:10.7498/aps.64.146301
高压下有序晶态合金Fe3Pt的低能声子不稳定性及磁性反常∗
Low energy phonon instabilities and magnetic abnormalities in ordered crystalline state alloys of Fe3Pt at high pressure
摘要
Abstract
The ordered crystalline Fe3Pt invar alloy is in a special magnetic critical state under which the lattice dynamic stability of the system is extremely sensitive to the external pressure. Using projection augmented plane wave method based on the density functional theory, we calculate the dependences of enthalpy and magnetism of different crystalline alloys of Fe3Pt on external pressure. The results reveal that the P 4/mbm structure is thermodynamically stable under pressures below 18.54 GPa. The total magnetic moments of P m¯3m, I4/mmm and DO22 structures decrease rapidly and oscillate near the ferromagnetic collapse critical pressure. Furthermore in I4/mmm and DO22 structures the atomic magnetic moment of Fe1 reverses near the critical pressure. At a pressure of 43 GPa, the micro-ferrimagnetic property in DO22 structure becomes apparently strengthened while its volume increases rapidly. The lattice dynamic calculation shows that the spontaneous magnetization of the system in ferromagnetic states induces the softening of the transverse acoustic phonon TA1(M) in the Fe3Pt of Pm¯3m structure, and there exists a strong spontaneous volume magnetostriction at pressures below 26.95 GPa. Especially, in the pressure range between the ferromagnetic collapse critical pressure 41.9 GPa and the magnetism completely disappearing pressure 57.25 GPa, the lattice dynamic stability is more sensitive to the pressure. The pressure induces the stability of the phonon spectrum of the system at pressures above 57.25 GPa.关键词
铁磁性坍塌临界压力/软模相变/第一性原理/Fe3Pt晶态因瓦合金Key words
ferromagnetic collapse critical pressure/soft mode phase transitions/first principles/crys-talline invar alloy Fe3Pt引用本文复制引用
成泰民,张龙燕,孙腾,张新欣,朱林,李林..高压下有序晶态合金Fe3Pt的低能声子不稳定性及磁性反常∗[J].物理学报,2015,(14):1-11,11.基金项目
国家自然科学基金(批准号:11374215)、吉林大学超硬材料国家重点实验室开放课题(批准号:201304)、中国博士后科学基金(批准号:200940501018)和辽宁省教育厅科学研究项目(批准号：L2014172)资助的课题.@@@@* Project supported by the National Natural Science Foundation of China (Grant No.11374215), the Open Project of State Key Laboratory of Superhard Materials (Jilin University, China)(Grant No.201304), the Scientific Research Foundation of the China Postdoctor Program (Grant No.200940501018), and the Scientific Study Project from Liaoning Ministry of Education, China (Grant No. L2014172) （批准号:11374215）
