电子束辐照下LaCoO3薄膜中产生的新结构

电子束辐照下LaCoO₃薄膜中产生的新结构

管翔翔^{1, 2}，沈  希¹，王伟鹏¹，张  静^{1, 2}，姚  湲¹，孙继荣^{1, 2}，禹日成^{1, 2*}

( 1．中国科学院物理研究所，北京凝聚态物理国家研究中心，北京  100190；

2．中国科学院大学 物理科学学院，北京101407)

摘 要 利用球差校正扫描透射电子显微学方法，研究了在电子束辐照作用下LaCoO₃/La_2/3Sr_1/3MnO₃/LaCoO₃三层膜中LaCoO₃的结构演化。在实验中观察到一种新的调制结构，确定了其在所观察截面上调制结构的晶胞为：a’ = a₀，b’ = a₀，夹角约为71.57°。（a₀为LaCoO₃赝立方结构的晶胞参数）。环形明场像的结果表明，LaCoO₃在电子束辐照下由具有3a₀周期的暗条纹结构演化为具有新周期的调制结构，并伴随氧空位的重新分布。本文研究的LaCoO₃薄膜中的结构演化是应变能、电子束辐照能量以及氧空位有序分布的形成能共同作用的结果，同时也为电子束辐照调控LaCoO₃薄膜的磁性提供了实验参考。

关键词  LaCoO₃；电子束辐照；调制结构；氧空位

中国分类号：TG115.21⁺5.3      

文献标识码：Adoi:10.3969/j.issn.1000-6281.2020.05.006

A new modulated structure of LaCoO₃ thin film induced by electron beam irradiation

GUAN Xing-xiang^{1, 2}，SHEN Xi¹，WANG Wei-peng¹，ZHANG Jing^{1, 2}，YAO Yuan¹，

SUN Ji-rong^{1, 2}，YU Ri-cheng^{1, 2*}

( 1.Beijing National Laboratory for Condensed Matter Physics，Institute of Physics，Chinese Academy of Sciences，Beijing 100190；2.School of Physical Sciences，University of Chinese Academy of Sciences，Beijing 101407，China）

Abstract  By using scanning transmission electron microscopy, the structural evolution of LaCoO₃ in LaCoO₃/ La_2/3Sr_1/3MnO₃/ LaCoO₃ film was investigated under the action of  electron beam irradiation (EBI). A new modulated structure is observed and the unit cell of the modulated structure in the projection plane along the transmission direction is determined asa’ = a₀, b’ = a₀, angle is about 71.57°(a₀ is the lattice parameter of the LaCoO₃ in the pseudo-cubic structure). The result of annular bright field image reveals that the redistribution of oxygen vacancies occurs in the transition from dark stripes structure with 3a₀ periodicity to the new modulated structure under EBI. In this study, the microstructural change is the result of the competition among strain energy, EBI induced energy and the forming energy of oxygen vacancy with ordering distribution. This work offers experimental reference for tuning the magnetism in LaCoO₃ film system.

Keywords  LaCoO₃; electron beam irradiation; modulated structure; oxygen vacancy

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