Local structure of (La,Sr)2CuO4 under uniaxial strain studied by polarized X-ray absorption spectroscopy
Local structure of (La,Sr)2CuO4 under uniaxial strain studied by polarized X-ray absorption spectroscopy
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DOI：
10.1016/j.jpcs.2006.05.012
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发表时间：
2006-09
影响因子：
4
通讯作者：
H. Oyanagi;N. Saini;A. Tsukada;M. Naito
中科院分区：
文献类型：
--
作者：
H. Oyanagi;N. Saini;A. Tsukada;M. Naito
利用面内极化Cu K边扩展X射线吸收精细结构（EXAFS）研究了在LaSrCuO 4和SrTiO 3衬底上分子束外延生长的优化掺杂T-（La，Sr）2CuO 4（LSCO）单晶薄膜的局域结构。数据分析结果表明，LSCO薄膜的局域结构（CuO 6八面体）受到约100 nm的应变。5×10− 3，与晶体学数据一致。虽然平面和顶点氧位移Δ RCuO与临界温度有简单的关系，但应变引起的氧位移（导致反Jahn-Teller或Jahn-Teller畸变）的大小小于平衡键长的0.1%。这表明，电子状态的应变依赖性涉及到一个不同的机制比一个纯电子模型在一个均匀的导电平面。拉伸应变下的LSCO薄膜的平面氧有一个大的局部变形的事实表明，不均匀性可能会影响临界温度，而不是顶端的氧位移。
Local structure of optimally doped T-(La,Sr)2CuO4(LSCO) single-crystal thin films grown by molecular-beam epitaxy on LaSrCuO4and SrTiO3substrates was studied by the in-plane polarized Cu K-edge extended X-ray absorption fine structure (EXAFS). The results of data analysis show that the local structure (CuO6octahedra) of LSCO thin films is strained by ca. 5×10−3in accordance with the crystallographic data. Although the planar and apical oxygen displacements ΔRCuOare related to the critical temperature in a simple relation, the magnitude of strain-induced oxygen displacements (leading to anti-Jahn–Tell or Jahn–Teller distortion) is less than 0.1% of the equilibrium bond length. This suggests that the strain dependence of electronic states involves a different mechanism than a purely electronic model in a homogeneous conducting plane. The fact that LSCO thin films under tensile strain have a large local distortion of planar oxygens indicates that inhomogeneity may affect the critical temperature rather than the apical oxygen displacement.