Electronic structure, magnetism, and antisite disorder in CoFeCrGe and CoMnCrAl quaternary Heusler alloys
Electronic structure, magnetism, and antisite disorder in CoFeCrGe and CoMnCrAl quaternary Heusler alloys
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DOI：
10.1103/physrevb.92.224413
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发表时间：
2015-12-10
影响因子：
3.7
通讯作者：
Alam, Aftab
中科院分区：
文献类型：
--
作者：
Enamullah;Venkateswara, Y.;Alam, Aftab
本文对CoFeCrGe （CFCG）和CoMnCrAl （CMCA）这两种具有自旋电子学应用前景的季系Heusler合金进行了理论和实验研究。磁化测试表明，CFCG和CMCA的饱和磁化强度分别为3 μ B， 866 K和0.9 μ B, 358 K。磁化值与我们的理论结果相当吻合，也符合半金属丰度的先决条件Slater-Pauling规则。这两种体系的显著区别在于它们的结构；CFCG结晶为全有序y型结构，而CMCA结晶为L2(1)无序结构。反位无序给第二种化合物增加了一些独特的性质，这是由于Al与Cr/Mn的概率相互交换位置引起的，由于Al和Cr/Mn的电负性相当，这种效应可能是预期的。从头算模拟预测了从半金属铁磁体到金属反铁磁体的独特转变，超过了合金中铝的临界过量浓度。
We present a combined theoretical and experimental study of two quaternary Heusler alloys CoFeCrGe (CFCG) and CoMnCrAl (CMCA), promising candidates for spintronics applications. Magnetization measurement shows the saturation magnetization and transition temperature to be 3 mu B, 866 K and 0.9 mu B, 358 K for CFCG and CMCA respectively. The magnetization values agree fairly well with our theoretical results and also obey the Slater-Pauling rule, a prerequisite for half metallicity. A striking difference between the two systems is their structure; CFCG crystallizes in fully ordered Y-type structure while CMCA has L2(1) disordered structure. The antisite disorder adds a somewhat unique property to the second compound, which arises due to the probabilistic mutual exchange of Al positions with Cr/Mn and such an effect is possibly expected due to comparable electronegativities of Al and Cr/Mn. Ab initio simulation predicted a unique transition from half metallic ferromagnet to metallic antiferromagnet beyond a critical excess concentration of Al in the alloy.