(La0．6Nd0．4)0．7Sr0．3MnO3薄膜的厚度依赖的结构与输运性  

THE THICKNESS-DEPENDENT STRUCTURAL AND TRANSPORT PROPERTIES OF EPITAXIAL (La_(0.6)Nd_(0.4))_(0.7)Sr_(0.3)MnO_3 FILMS

作　　者：金绍维[1] 李金光[1] 单会会[1] 吴文彬[2] 周先意[2] 

机构地区：[1]安徽大学物理与材料科学学院,合肥230039 [2]中国科学技术大学合肥微尺度物质科学国家实验室,合肥230026

出　　处：《低温物理学报》2008年第2期120-124,共5页Low Temperature Physical Letters

基　　金：国家自然科学基金(项目编号:50421201);安徽省自然科学基金(项目编号:KJ2007B031)资助的课题~~

摘　　要：厚度为6-100nm的（La0．6Nd0．4）0．7Sr0．3MnO3（LNSMO）薄膜是由脉冲激光沉积生长在SrTiO3[STO（001）]衬底上．X-射线衍射（XRD）线扫描、一摇摆曲线和倒空间衍射显示，随着膜厚（t）的变化，薄膜的结构经历了由完全应变到部分弛豫的变化．电阻测量显示存在两个不同的厚度依赖的金属一绝缘体转变温度（Tp），对于应变的薄膜（t≤17nm），Tp敏感地依赖于双轴应变和膜厚；而对较厚的薄膜（t≥35rim），Tp对于膜厚是较小敏感的．这个厚度依赖的输运性的变化可被解释为菱形LNSMO的角度畸变诱导的应变和弛豫．我们的结果表明金属-绝缘体转变温度和相分离都受薄膜的应变态控制．Epitaxial （La0. 6 Nd0. 4 ）0.7 Sr0. 3 MnOa （LNSMO） films with 6 - 100 nm thick were grown on SrTiOa[STO（001）] substrates by using pulse laser ablation. The structure of the LNSMO films was examined fully by X-ray （2θ=ω scan, ω-rocking curves, and reciprocal space maps） radiation. As the LNSMO film thickness, t, is increased, the films evolve from being fully strained to partially relaxation, and while there exist two distinct thickness ranges where different thickness dependence of transport properties was observed. For thickness t≤ 17 nm, the metal-insulator transition temperature Tp is extremely sensitive to the biaxial strain and thickness, and for t≥35 nm, Tp is weakly dependent on the film thickness. This variation of thickness dependence could be explained by the angular-distortion induced strain and relaxation of rhombohedral LNSMO structure. The results indicate that Tp （To） and phase separation are all controlled by the strain states of the films.

关 键 词：外延薄膜 晶格失配应变 金属-绝缘体转变 

分 类 号：O484[理学—固体物理]