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Thickness Impacts of Vacancy Defects in Epitaxial La0.7Sr0.3MnO3Thin Films Using Slow Positron Beam
刘建党,成斌,杜淮江,叶邦角*
Author NameAffiliationE-mail
刘建党 Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China  
成斌 Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China  
杜淮江 Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China  
叶邦角* Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China bjye@ustc.edu.cn 
Abstract:
Thickness effects of thin La0.7Sr0.3MnO3 (LSMO) films on (LaAlO3)0:3(Sr2AlTaO6)0:7 sub-strates were examined by a slow positron beam technique. Doppler-broadening line shape parameter S was measured as a function of thickness and differnt annealing conditions. Re- sults reveal there could be more than one mechanism to induce vacancy-like defects. It was found that strain-induced defects mainly influence the S value of the in situ oxygen- ambience annealing LSMO thin films and the strain could vanish still faster along with the increase of thickness, and the oxygen-deficient induced defects mainly affect the S value of post-annealing LSMO films.
Key words:  Thin film, Giant magnetoresistance, Slow positron beam, Defect
FundProject:
外延生长La0.7Sr0.3MnO3薄膜厚度对缺陷影响的慢正电子分析
Jian-dang Liu,Bin Cheng,Huai-jiang Du,Bang-jiao Ye*
摘要:
采用脉冲激光沉积方法在(LaAlO3)0:3(Sr2AlTaO6)0:7衬底上外延生长了La0.7Sr0.3MnO3薄膜,并采用慢正电子束方法分析了薄膜在不同厚度和不同退火气氛下参数S的变化. 分析表明,薄膜中包含两种机制引入的氧空位,分别是薄膜生长气氛中氧压偏低造成薄膜的氧缺乏和由于薄膜应变引入空位型缺陷. 当薄膜厚度较薄时,应变造成的晶格畸变化比较大,当薄膜的厚度大于11 nm时,薄膜的应变驰豫已经比较完全. 原位退火的样品中正电子主要是被氧缺乏引起的氧空位捕获. 在氧气中退火的样品,S随厚度的变化反映了应变对薄膜微结构的影响.
关键词:  薄膜,巨磁阻,慢正电子束,缺陷
DOI:10.1088/1674-0068/23/06/685-688
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