題  目：Disorder-induced topological phase transitions from trivial-to-nontrivial insulators

内容簡介：Occurrence of topological Anderson insulator (TAI) in HgTe quantum well suggests that when time-reversal symmetry (TRS) is maintained, the pertinent topological phase transition, marked by re-entrant 2e^2/h quantized conductance contributed by helical edge states, is driven by disorder. In this talk, I will show that when TRS is broken, the physics of TAI becomes even richer. The pattern of longitudinal conductance and nonequilibrium local current distribution displays novel TAI phases characterized by nonzero Chern numbers, indicating the occurrence of multiple chiral edge modes. Unlike topological insulators with time-reversal symmetry that, in the absence of an external magnetic field, support only a single quantized conductance TAI, systems without time-reversal symmetry exhibit novel TAI by tuning either disorder or Fermi energy (in both topologically trivial and nontrivial phases), drives transitions between distinct TAI phases  characterized by jumps of the quantized conductance from 0 to e^2/h and from e^2/h to 2e^2/h. An effective medium theory based on the Born approximation yields an accurate description of different TAI phases in parameter space.

報告人：香港科技大學物理系  王向榮  教授

報告人簡介：1984年畢業于武漢大學物理系，同年通過中美聯合招收物理研究生選撥考試(CUSPEA) 赴美深造；1990年在美國羅徹斯特大學(University of Rochester)獲博士學位；是多所學校和研究機構的客座教授。王教授在凝聚态理論領域具有豐富研究經驗，研究領域包括量子霍爾效應，二維電子氣量子輸運，超晶格以及量子糾纏與量子計算；創造性地提出了超晶格中電流自振蕩的極限環理論；從理論上揭示了磁動力學中磁疇壁運動的機理，為完全理解磁疇壁的運動規律提供了理論基礎；已在國際權威學術雜志發表論文過百篇。

主持人：陳芝得  教授

時  間：2016年11月21日（周一）下午3：00始

地  點：南海樓338室

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太阳集团1088vip/網絡空間安全學院

2016年11月16日