磁学室学术报告（2014-6）

来源：admin 发布时间：2016-06-17

报告题目：Tuning the quasi two-dimensional electron gas at complex oxide interface

报告人: 谢燕武 (美国斯坦福大学)

报告时间：2014年10月16日（周四） 15:00-17:00

报告地点： M236会议室

报告摘要：
Since its discovery in 2004, LaAlO3/SrTiO3 heterointerface has been a paradigm system in studying the emergent phenomena
at the oxide interface. Here, I present two unusual ways to tune the interfacial quasi two-dimensional electron gas (q2DEG) from
LaAlO3 surface, which are intriguing in that surface modification remotely toggles a proximate interface. First, the q2DEG can be
locally tuned by using biased atomic force microscope probe [1]. Our studies show that this is caused by the accumulation of charge
on the LaAlO3 surface [2, 3]. Second, we found that the q2DEG can be dramatically tuned by surface adsorption of common polar
solvents such as acetone, ethanol and water [4]. This strong surface-interface coupling provides deep insight to the origin of the q2DEG.
Most significantly, adsorbates induce an insulator to metal transition when the thickness of the LaAlO3 is 3 unit cells, suggesting sensor
applications with extremely large sensitivity. Furthermore, by optimizing these two surface controls of LaAlO3, we enhance the Hall mobility
of the q2DEG to >20,000 cm2V-1s-1 [5]. This progress provide us a chance to clearly study the quantum transport of the q2DEG, where we
observed novel plateaus in Hall conductivity, for the first time in d-electron system [6]. These plateaus have apparent 4-fold degeneracy,
suggesting a magnetic break-down transition at the Fermi surface.
[1] C. Cen et al., Nature Mater. 7, 298 (2008).
[2] Y. Xie et al., Nano Lett. 10, 2588 (2010).
[3] Y. Xie et al., Adv. Mater. 23, 1744(2011).
[4] Y. Xie et al., Nature Commun. 2, 494 (2011).
[5] Y. Xie et al., Adv. Mater. 25, 4735 (2013).
[6] Y. Xie et al., Solid State Commun. 197, 25 (2014)

个人简介：
谢燕武博士是美国斯坦福大学Geballe先进材料实验室的研究助理。2001年和2004年在吉林大学先后取得学士和硕士学位，
2007年在中国科学院物理研究所取得博士学位。之后先后在燕山大学亚稳材料制备技术与科学国家重点实验室、日本东京大学
先端材料研究所和美国斯坦福大学Geballe先进材料实验室从事研究工作。主要从事复杂氧化物界面电子学的实验前沿研究，
精通研究复杂氧化物的多种最先进的实验技术，能在原子尺度实现可控制备、表征探测与物性调控。研究工作既注重探索新奇
的界面量子现象，又注重发展面向未来的新型电子器件。至今在《Nature Materials》、《Nature Communications》、《Advanced Materials》
和《Nano Letters》等国际主流学术期刊上发表研究论文共40余篇，是《Advanced Materials》和《Nano Letters》等多个学术期刊审稿人。

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