Mn_(2)NiSn掺杂Ni、Co体系的结构与磁性研究  

The structures and magnetisms of Ni/Co-doped Mn_(2)NiSn

作　　者：李歌天[1] 张强强 柳祝红[1] LI Ge-Tian;ZHANG Qiang-Qiang;LIU Zhu-Hong(Department of Physics,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学物理系,北京100083

出　　处：《原子与分子物理学报》2021年第5期149-156,共8页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(11774026)。

摘　　要：本文通过在Heusler合金Mn_(2)NiSn中掺杂Ni、Co元素对其结构与磁性交换作用变化进行了研究.结果表明,在Mn_(2-x)Ni_(1+x)Sn体系中,随着Ni逐渐替代Mn,合金结构会由立方XA逐渐向L21结构转变.由于Ni原子相对于Mn原子具有较小的原子半径,Ni2MnSn相对于Mn_(2)NiSn体积大概收缩1.2%.Mn含量的减少使得最近邻的Mn(A)-Mn(B)间反铁磁交换作用减弱,导致居里温度由x=0时的519 K接近线性的降低到x=1时的340 K.当用Co元素替换部分Mn元素时,即Mn_(2-y)Co_(y)NiSn中,复杂的原子占位使得Mn(A)-Mn(B)交换作用降低的同时伴随着Co-Mn之间铁磁交换作用的增强,两者交换作用的竞争导致居里温度先降低后升高,临界点出现在y=0.3处.在Mn_(2)Ni_(1-z)Co_(z)Sn体系中,当Co替代部分Ni时,由于Ni-Mn之间的交换作用小于Co-Mn之间的交换作用,交换作用的增强导致居里温度随着Co含量的增加逐渐升高.室温下的饱和磁化强度也随着掺杂量的增大逐渐增大.The influences of Co and Ni doping on the structure and magnetic interaction of Heusler alloy Mn_(2)NiSn are studied in this paper.It is found that the structure of the alloy changes from cubic XA to L2_(1)in Mn_(2-x)Ni_(1+x)Sn when x increases from 0 to 1.The volume of Ni 2 MnSn shrinks about 1.2%relative to Mn_(2)NiSn because the radius of Ni atom is smaller than that of Mn atom.The replacement of Mn with Ni weakens the antiferromagnetic exchange between Mn(A)-Mn(B),resulting in the Curie temperature decreases from 519 K in Mn_(2)NiSn to 340 K in Ni_(2)MnSn.When partial of Mn is replaced by Co in Mn_(2-y)Co_(y)NiSn,the competition of the exchange interaction between Mn(A)-Mn(B)and between Co-Mn leads to the Curie temperature decreasing first and then increasing.When Co replaces Ni in Mn_(2)Ni_(1-z)Co_(z)Sn,the Curie temperature increases with the increase of Co content due to exchange interaction between Ni-Mn is smaller than that between Co-Mn.At room temperature,the saturation magnetization increases with the increase of doping amount.

关 键 词：HEUSLER合金 原子占位 磁交换作用 

分 类 号：O65[理学—分析化学]