Li Guowei, Zhang Baomin, Baluyan Tigran, Rao Jiancun, Wu Jiquan, Novakova Alla A, Rudolf Petra, Blake Graeme R, de Groot Robert A, Palstra Thomas T M
Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.
School of Physics and Technology, University of Jinan , 336 West Road of Nan Xinzhuang, 250022 Jinan, P. R. China.
Inorg Chem. 2016 Dec 19;55(24):12912-12922. doi: 10.1021/acs.inorgchem.6b02257. Epub 2016 Nov 30.
FeSe exists as a hexagonal NiAs-like crystal structure with a large number of ordered intrinsic vacancies. It is an ideal candidate for studying the effect of defects on properties such as magnetism and electrical transport. In this work, highly crystalline FeSe with the 3c crystal structure was synthesized by a solid-state reaction. Sharp changes in the magnetization at 100 K confirm a rotation of the spins from the ab plane to the c axis with decreasing temperature. We observe an interesting metal-insulator transition at the same temperature as the spin-direction changes. We propose that locked spins in the grain boundaries induce electron localization and result in the metal-insulator transition. Electron localization is confirmed by X-ray photoelectron spectroscopy of the Fe 2p peaks, which exhibit two characteristic satellite peaks. This mechanism is also verified by comparing it with the properties of the 4c-FeSe crystal structure.
FeSe以具有大量有序本征空位的六方NiAs类晶体结构存在。它是研究缺陷对磁性和电输运等性质影响的理想候选材料。在这项工作中，通过固态反应合成了具有3c晶体结构的高结晶度FeSe。100 K时磁化强度的急剧变化证实了随着温度降低，自旋从ab平面旋转到c轴。我们在与自旋方向变化相同的温度下观察到了有趣的金属-绝缘体转变。我们提出，晶界中锁定的自旋诱导电子局域化并导致金属-绝缘体转变。通过对Fe 2p峰的X射线光电子能谱证实了电子局域化，该能谱显示出两个特征卫星峰。通过将其与4c-FeSe晶体结构的性质进行比较，也验证了这一机制。
