报告题目：Atomic structures and related properties of broken symmetry states using advanced electron microscopy and spectroscopy
报 告 人：金磊博士（德国于利希研究中心终身研究员）
时 间：2018年05月15日 晚上18：00
地 点：物理学院新楼五楼大报告厅
报告摘要：
The states that relate to the breaking of translational symmetry (broken symmetry states, such as dislocations, heterointerfaces, domain walls and surfaces) have attracted great attention owning to their novel properties/functionalities that differ from the matrix bulk. For example, the electrical resistance of individual dislocations in singlecrystalline SrTiO3 can be switched [1] and the conductivity of domain walls in ferroic BiFeO3 and Pb(Zr,Ti)O3 have also been reported [2,3]. The intrinsically small size of the broken symmetry states where the functionalities are confined provides additional advantage for future applications, particularly in the field of high-density storage. However, a full understanding of the structure-property relationships of these states becomes challenging for the same reason. Unravelling these relationships is of critical importance in order to learn how to control these states towards functionalization.
In this contribution, we present our recent studies of the atomic structures and related properties of various broken symmetry states in perovskite oxides by means of advanced (scanning) transmission electron microscopy and spectroscopy. The observed structures are compared quantitatively with models based on first-principle density functional theory calculations. We also demonstrated that, with the application of combined chromatic and spherical aberration correction, the Y-Y atom pairs in b-axis oriented YAlO3: Ce with a nominal separation of 57 pm can be imaged with 200 keV electrons. The improvement of spatial resolution is expected to benefit future structural investigations.
The author would like to thank I. Lindfors-Vrejoiu, F. Gunkel, Y. Zeng and H. Wang for
providing the thin film samples, P.X. Xu and T. Schulthess for performing theoretical
calculations, Prof. C.L. Jia, J. Barthel, L. Lu, X.Y. Zhong, H.C. Du, Prof. R.E. DuninBorkowski and Prof. K.W. Urban for collaborations.
[1] K Szot el al., Nature Mater. 5 (2006) 312-320.
[2] J Seidel et al., Nature Mater. 8 (2009) 229-234.
[3] L Feigl et al., Nature Commun. 5 (2014) 4677.
邀请人：王建波教授
