Physics Colloquium - Spin and Pseudospins in 2D Semiconductors

Event Date: 

Tuesday, December 2, 2014 - 4:00pm

Event Location: 

  • Broida 1640

Event Contact: 

Speaker:

Xiaodong Xu, University of Washington

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 VIB transition metal dichalcogenides. I will first show that these new 2D semiconductors behave as remarkable excitonic systems, providing an ideal laboratory for optical manipulation and electrical control of valley degrees of freedom. I will then 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 and single quantum emitters in monolayers.