21 Nov
2014
21 Nov
'14
1:15 p.m.
Please post and forward to your groups
______________________
CENTER FOR EXCITONICS
Optoelectronics of 2D Materials
November 25, 2014 at 4:30 PM/ 6-120
Xiaodong Xu
University of Washington
[xiaodongXu-02]
Abstract:
Electronic valleys are extrema of Bloch energy bands in momentum space. Having multiple
valleys gives the electron states pseudospin degrees of freedom in addition to their real
spin. In this talk, I will discuss our experimental progress on the investigation of spins
and pseudospins using atomically thin semiconductors, which are either single or bilayer
group VI transition metal dichalcogenides [1-3]. These new 2D semiconductors behave as
remarkable excitonic systems, providing an exciting laboratory for optical, electrical and
magnetic control of the valley degrees of freedom. I will also discuss strong coupling
effects between spin, valley, and layer pseudo-spins in bilayers, which lead to spin
polarization in electronic bands in the presence of bulk inversion symmetry and allow
electrical control of spin states. I will conclude the talk with the discussion of
spatially indirect exciton properties in monolayer semiconducting heterostructures [4] and
single quantum emitters in monolayers [5].
References
[1] Xu et al., Nature Physics 10, 343(2014).
[2] Jones et al., Nature Nanotechnology 8, 634-638 (2013).
[3] Aivazian et al., http://arxiv.org/abs/1407.2645.
[4] Rivera et al., http://arxiv.org/abs/1403.4985;
[5] He et al., http://arxiv.org/abs/1411.2449.
Bio:
Xiaodong Xu has been an Assistant Professor in the Department of Physics and the
Department of Materials Science and Engineering at the University of Washington since
Sept. 2010. He received his PhD (Physics, 2008) from the University of Michigan and then
performed postdoctoral research (2009-2010) at the Center for Nanoscale Systems at Cornell
University. His nanoscale optoelectronics group at University of Washington focuses on
creation, control, and understanding of novel optoelectronic devices based on
two-dimensional quantum materials. Selected awards include DAPRA YFA, NSF Early Career
Award, DoE Early Career Award, Cottrell Scholar Award, and IUPAP Young Scientist Prize in
Semiconductor Physics.
Light refreshments will be served
