Mixed ground state in Fe-Ni Invar alloys
Mixed ground state in Fe-Ni Invar alloys
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DOI：
10.1016/j.jallcom.2021.158605
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发表时间：
2021-01-22
影响因子：
6.2
通讯作者：
Maiti, Kalobaran
中科院分区：
文献类型：
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作者：
Acharya, S. S.;Medicherla, V. R. R.;Maiti, Kalobaran
通过对Fe_（1-x）Ni_x合金（x = 0.2，0.3，0.4，0.5，0.6，0.7，0.9）的电子结构的X射线光电子能谱（XPS）研究，探讨了因瓦合金的基态性质。当居里温度远高于室温时，所有合金都表现出软铁磁行为，而因瓦合金Fe_（0.6）Ni_（0.4）表现出反常行为。此外，因瓦合金的磁阻变得非常负，而端部构件具有正磁阻。Invar合金的芯能级谱在20 K以下出现了一个明显的新特征，而其它Fe-Ni合金在10 K以下没有温度依赖性。有趣的是，与深芯能级（2s，2 p）相比，因瓦合金的Fe和Ni的浅芯能级光谱（3s，3 p）在低温下显示出更强的偏离，表明晶场效应。看来，在低于20 K的温度下，在α相中的Fe上有大量具有低磁矩（0.5 μ B）的反铁磁相沉淀。低温下负磁阻、反常磁化以及低温下芯能级出现的异常新特征的发现，为因瓦合金基态存在混合相提供了证据。(C)2021爱思唯尔有限公司版权所有。
We investigate the ground state properties of Invar alloys via detailed study of the electronic structure of Fe1-xNix alloys (x = 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.9) employing x-ray photoelectron spectroscopy (XPS). While all the alloys exhibit soft ferromagnetic behavior with Curie temperature much higher than the room temperature, the results for invar alloy, Fe0.6Ni0.4 exhibit anomalous behavior. Moreover, the magnetoresistance of the Invar alloy becomes highly negative while the end members possess positive magnetoresistance. The core level spectra of the Invar alloy exhibit emergence of a distinct new feature below 20 K while all other Fe-Ni alloys exhibit no temperature dependence down to 10 K. Interestingly, the shallow core level spectra (3s, 3p) of Fe and Ni of the Invar alloy reveal stronger deviation at low temperatures compared to the deep core levels (2s, 2p) indicating crystal field effect. It appears that there is a large precipitation of antiferromagnetic phase below 20 K possessing low magnetic moment (0.5 mu B) on Fe within the a phase. The discovery of negative magneto-resistance, anomalous magnetization at low temperature and the emergence of unusual new features in the core levels at low temperature provide an evidence of mixed phase in the ground state of Invar alloys. (C) 2021 Elsevier B.V. All rights reserved.