Heusler合金Fe_2CrGa的磁性与结构  

Magnetic property and structure of Heusler alloy:Fe_2CrGa

作　　者：朱伟[1] 刘恩克[1] 张常在[1,2] 秦元斌[1] 罗鸿志[3] 王文洪[1] 杜志伟[4] 李建奇[1] 吴光恒[1] 

机构地区：[1]中国科学院物理研究所磁学国家重点实验室,北京100190 [2]内蒙古大学物理科学与技术学院,呼和浩特010021 [3]河北工业大学材料科学与工程学院,天津300130 [4]北京有色金属研究总院分析测试中心,北京100088

出　　处：《物理学报》2012年第2期436-445,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51031004);国家重点基础研究发展计划(批准号:2010CB833102)资助的课题~~

摘　　要：采用KKR-CPA-LDA方法研究了不同混乱占位时Fe_2CrGa合金基态的电子结构和磁结构.基态能量表明Fe_2CrGa合金更倾向于形成Hg_2CuTi型有序结构,而不是L2_1结构.能态密度(DOS)分析进一步揭示受晶体场影响的磁性原子内部交换作用是使Fe_2CrGa合金形成Hg_2CuTi型有序结构的主要原因.测量了不同热处理所得Fe_2CrGa合金的居里温度和分子磁矩,发现原子占位有序化可以在137K温度范围内调控合金的居里温度.分子磁矩随有序化占位也有相应变化,分布在2.28μ_B/f.u.—2.48μ_B/f.u.之间.理论计算和实验对比可证明Fe_2CrGa合金是Hg2CuTi型Heusler合金.The KKR-CPA-LDA method was used to calculate the electronic and the magnetic structures of Fe_2CrGa alloy.The results indicate that Fe_2CrGa alloy prefers to crystallize in Hg_2CuTi-type structure rather than L2_1 one.The analysis of density of states reveals that the intra-atomic exchange splitting affected by crystal field plays an important role in forming the Hg2CuTi-type structure. The molecular magnetic moments measured experimentally are in a range of 2.28—2.48_（μB） / f.u.,which is very close to that expected theoretically by the calculations based on the Hg_2CuTi-type structure,but not based on the L2_1 structure.The experimental results also show that the Curie temperature of Fe_2CrGa alloy can be continuously manipulated from 308K to 445K by heat-treating under the various conditions,indicating a high sensitivity of the exchange interaction to the atomic ordering in this system.

关 键 词：Fe_2CrGa 磁性与结构 相干势近似 HEUSLER合金 

分 类 号：O482.5[理学—固体物理]