The thickness-dependent metal–insulator transition is observed in meta-stable orthorhombic SrIrO3 thin films synthesized by pulsed laser deposition. SrIrO3 films with thicknesses less than 3 nm demonstrate insulating behaviour, whereas those thicker than 4 nm exhibit metallic conductivity at high temperature, and insulating-like behaviour at low temperature. Weak/Anderson localization is mainly responsible for the observed thickness-dependent metal–insulator transition in SrIrO3 films. Temperature-dependent resistance fitting shows that electrical-conductivity carriers are mainly scattered by the electron–boson interaction rather than the electron–electron interaction. Analysis of the magneto-conductance proves that the spin–orbit interaction plays a crucial role in the magneto-conductance property of SrIrO3.

SrIrO3

文章发表在J. Phys.: Condens. Matter 25, 125604 (2013).

全文链接:http://iopscience.iop.org/0953-8984/25/12/125604/


我们用第一性原理计算研究了石墨烯吸附不同IVA族元素后的物理性质,包括吸附能、几何结构和电子结构。我们发现随着原子序数增加,吸附能逐渐降低。从碳到铅,石墨烯与他们之间的相互作用从强烈的共价键逐渐向弱的范德瓦耳斯键过渡,对于碳和硅,bridge位吸附是最稳定的,而对于锗、锡、铅,bridge位和top位都是稳定的。而且这些原子吸附在石墨烯上,都能表现出磁性,这种磁性的起源是来自于吸附原子局域的p轨道。

本论文发表在JAP.

全文链接: http://jap.aip.org/resource/1/japiau/v107/i11/p114311_s1?bypassSSO=1

4 June, 2010

  

 

 

A series of layered n-ABO3-doped Aurivillius structures Bi4Ti3O12 (BTO) thin films are synthesized on (001) SrTiO3 (STO) substrates by pulsed laser deposition, where n represents the number of ABO3 perovskite. X-ray diffraction substantiates that these films have expected layered Aurivillius structures. Furthermore, the microstructure of these samples is “systematically”
characterized by transmission electron microscopy. It is found that the structure of n-STO-doped BTO becomes unstable when n is equal to 3, as revealed by the occurrence of intergrowth. Similar phenomenon is observed in n-LaFeO3-doped BTO; the layered Aurivillius structure is totally collapsed in the case of n as high as 2.5. In contrast, 3-BiFeO3-doped BTO still keeps perfect Aurivillius structure. The above-observed structural stabilities of these materials are explained by the theoretical formation enthalpy calculated by the density functional theory. This work provides the necessary information to explore the multifunctionality based on Aurivillius n-ABO3–BTO oxides.

BTO

This paper is published on J. Mater. Res..

Link to the full text: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8756918

31 Oct, 2012

  

日本JAIST教授T. Ozaki受周健老师邀请,于2012年8月17日至24日访问南京大学。在南大期间,Ozaki教授给研究生开设了关于第一性原理计算方面的短期课程。

Ozaki教授是著名的第一性原理课程OpenMX的主要开发者,也是国际上知名的计算材料科学专家。他这次课程主要包含以下内容: 

  1. 计算材料学简介
  2. 材料电子结构回顾
  3. 密度泛函理论基础
  4. 第一性原理计算
  5. 分子和固体的密度泛函理论计算
  6. 第一性原理分子动力学
  7. 大规模电子结构计算
  8. 电子输运计算
  9. 相对论效应和非共线磁性密度泛函理论

大概有五十名研究生选修了该课程,其中还包括南京大学和其它高校的一些老师也参加了本次课程。整个课程内容为18小时。

特别感谢南京大学研究生院对Ozaki教授访问的资金支持。

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Sept. 2012.