Chaboy J, Lázpita P, Barandiarán J M, Gutiérrez Jon, Fernández-Gubieda Maria Luisa, Kawamura N
Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain.
J Phys Condens Matter. 2009 Jan 7;21(1):016002. doi: 10.1088/0953-8984/21/1/016002. Epub 2008 Dec 1.
The proper annealing of Ni(51)Mn(28)Ga(21) ribbon alloy gives rise to an increase of the saturation magnetization and of the magnetic order T(C) (up to 20 K) and martensitic transition T(M) (up to 10 K) temperatures. The combined x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) studies indicate that the annealing treatment drives the alloy to a more ordered structure without significantly affecting the local structure in terms of interatomic distances and bonding geometry. By contrast, the annealing strongly affects the near-edge absorption at the Mn K-edge while no effect is observed at either the Ni or Ga K-edge. These results suggest that annealing leads to a modification of the electronic structure of the Mn atoms while that of Ni and Ga atoms remains unvaried. However, strong XMCD signals are detected at both Ni and Ga K-edges whose amplitude increases after annealing. These results point out that despite the change of the magnetic properties of the system being mainly associated with the modification of the electronic properties of the Mn atoms, both Ni and Ga may play a non-negligible role through the polarization of the conduction band.
对Ni(51)Mn(28)Ga(21)带状合金进行适当退火，会使饱和磁化强度以及磁有序温度T(C)（提高至20 K）和马氏体转变温度T(M)（提高至10 K）增加。结合X射线吸收光谱(XAS)和X射线磁圆二色性(XMCD)的研究表明，退火处理使合金趋向于更有序的结构，而在原子间距离和键合几何结构方面，对局部结构没有显著影响。相比之下，退火对Mn K边的近边吸收有强烈影响，而在Ni或Ga K边均未观察到影响。这些结果表明，退火导致Mn原子的电子结构发生改变，而Ni和Ga原子的电子结构保持不变。然而，在Ni和Ga K边均检测到强烈的XMCD信号，其幅度在退火后增加。这些结果指出，尽管体系磁性能的变化主要与Mn原子电子性能的改变有关，但Ni和Ga都可能通过导带的极化发挥不可忽视的作用。
