Competition of L21 and XA structural ordering in Heusler alloys X2CuAl (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni)
Competition of L21 and XA structural ordering in Heusler alloys X2CuAl (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni)
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Heusler 合金 X2CuAl 中 L2(1) 和 XA 结构排序的竞争（X = Sc、Ti、V、Cr、Mn、Fe、Co、Ni）
DOI：
10.1016/j.jallcom.2015.11.207
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发表时间：
2016-04-25
影响因子：
6.2
通讯作者：
Wu, Guangheng
中科院分区：
文献类型：
--
作者：
Luo, Hongzhi;Xin, Yuepeng;Wu, Guangheng
在Heusler合金X2CuAl(X=Sc，Ti，V，Cr，Mn，Fe，Co，Ni)中观察到了常规L2(1)有序和XA逆有序之间的竞争。在X2CuAl中，纯X元素的晶体结构强烈影响了铜的晶位择优。当X元素具有紧密堆积的fcc或hcp结构(Sc，Ti，Co和Ni)时，铜优先进入(1/4，1/4，1/4)位置形成L2(1)结构，而当X具有体心立方结构(V，Cr，Mn，Fe)时，铜优先进入(1/2，1/2，1/2)位置形成XA结构。因此，在讨论Heusler合金中的晶位择优时，还应考虑纯X元素的晶体结构和价电子数。发现Mn2CuAl是一种自旋无间隙半导体(SGS)，具有完全补偿的总磁矩。在此基础上，讨论了SGS设计的可能原则。最后，除V2CuAl和Cr2CuAl外，X2CuAl合金均具有负形成能。(C)2016年，由爱思唯尔出版。
A competition between the conventional L2(1) ordering and inverse XA ordering has been observed in Heusler alloys X2CuAl (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni). In X2CuAl, the site preference of Cu is strongly influenced by the crystal structure of pure X elements. When X element has a close-packed FCC or HCP structure (Sc, Ti, Co and Ni), Cu prefers entering the (1/4, 1/4, 1/4) position and forms the L2(1) structure, but when X has a BCC structure (V, Cr, Mn, Fe), Cu prefers entering the (1/2, 1/2, 1/2) position and forms the XA structure. So the crystal structure of pure X element should also be considered together with number of valence electrons when discussing the site preference in Heusler alloys. Mn2CuAl is found to be a spin gapless semiconductor (SGS) with fully-compensated total moment. Based on this, a possible rule to design SGS has been discussed. Finally, X2CuAl alloys all have a negative formation energy except for V2CuAl and Cr2CuAl. (C) 2016 Published by Elsevier B.V.