Amorphous nonstoichiometric oxides with tunable room-temperature ferromagnetism and electrical transport  

非晶、非化学计量比的氧化物及其室温铁磁性和电输运的调控

作　　者：Qinghao Li Ruimin Qiao Apurva Mehta Weiming Lü Tie Zhou Elke Arenholz Cheng Wang Yanxue Chen Li Li Yufeng Tian Lihui Bai Zahid Hussain Rongkun Zheng Wanli Yang Shishen Yan 李庆浩;乔瑞敏;Apurva Mehta;吕伟明;周铁;Elke Arenholz;王诚;陈延学;李莉;田玉峰;柏利慧;Zahid Hussain;郑荣坤;杨万里;颜世申(Spintronics Institute.University of Jinan,Jinan 250022,China;Advanced Light Source,Lawrence Berkeley National Laboratory,Berkeley,CA 94720,USA;SLAC National Accelerator Laboratory.Menlo Park,CA 94025,USA;School of Physics,State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,China;Cornell High Energy Synchrotron Source,Cornell University,Ithaca,NY 14853,USA;School of Physics,The University of Sydney,Sydney,New South Wales 2006,Australia)

机构地区：[1]Spintronics Institute.University of Jinan,Jinan 250022,China [2]Advanced Light Source,Lawrence Berkeley National Laboratory,Berkeley,CA 94720,USA [3]SLAC National Accelerator Laboratory.Menlo Park,CA 94025,USA [4]School of Physics,State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,China [5]Cornell High Energy Synchrotron Source,Cornell University,Ithaca,NY 14853,USA [6]School of Physics,The University of Sydney,Sydney,New South Wales 2006,Australia

出　　处：《Science Bulletin》2020年第20期1718-1725,M0003,共9页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China (11434006, 11774199, and 51871112);the National Basic Research Program of China (2015CB921502);the 111 Project B13029;supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DEAC02-76SF00515。

摘　　要：Material functionalities strongly depend on the stoichiometry,crystal structure,and homogeneity.Here we demonstrate an approach of amorphous nonstoichiometric inhomogeneous oxides to realize tunable ferromagnetism and electrical transport at room temperature.In order to verify the origin of the ferromagnetism,we employed a series of structural,chemical,and electronic state characterizations.Combined with electron microscopy and transport measurements,synchrotron-based grazing incident wide angle X-ray scattering,soft X-ray absorption and circular dichroism clearly reveal that the roomtemperature ferromagnetism originates from the In0.23Co0.77O1-v,amorphous phase with a large tunable range of oxygen vacancies.The room-temperature ferromagnetism is tunable from a high saturation magnetization of 500 emu cm-3 to below 25 emu cm-3,with the evolving electrical resistivity from5×103μΩ cm to above 2.5×105 μΩ cm.Inhomogeneous nano-crystallization emerges with decreasing oxygen vacancies,driving the system towards non-ferromagnetism and insulating regime.Our work unfolds the novel functionalities of amorphous nonstoichiometric inhomogeneous oxides,which opens up new opportunities for developing spintronic materials with superior magnetic and transport properties.材料的性能通常依赖并受限于化学计量比、晶体结构及其均匀性.本文提出制备非晶、非化学计量比、非均匀氧化物,在室温下实现了In0.23Co0.77O1-v薄膜的铁磁性和电输运性质的大幅度调控.为了验证In0.23CoO1-v薄膜的铁磁性起源,作者进行了一系列的结构、化学和电子态表征,综合分析高分辨电镜测量、电输运测量、同步辐射掠入射X射线散射、软X射线吸收谱、磁圆二色性谱,说明室温铁磁性来源于含大量氧空位的In0.23Co0.77O1-v非晶相.通过减少氧空位浓度,室温铁磁性可从高饱和磁化强度500 emu/cm3调节到25 emu/cm3以下,同时电阻率从5×103μΩcm调节到2.5×105μΩcm以上.随着氧空位的减少,产生In0.23Co0.77O1-v纳米晶,促使In0.23Co0.77O1-v铁磁半导体转化为非磁性的绝缘体.本研究揭示了非晶、非化学计量比、非均匀氧化物的新功能,为开发具有优异磁性和电输运性质的自旋电子材料开辟了新的途径.

关 键 词：Amorphous oxide Room-temperature ferromagnetism Grazing incident wide angle X-ray SCATTERING Soft X-ray spectroscopy 

分 类 号：TB383.2[一般工业技术—材料科学与工程]