Researchers manage to efficiently generate long-lived valley polarization in 2D heterostructures

Researchers from the US, Japan and Korea report an efficient generation of microsecond-long-lived valley polarization in WSe2/MoS2 heterostructures by exploiting the ultrafast charge transfer processes in the heterostructure that efficiently creates resident holes in the WSe2 layer.

Ultrafast charge transfer process in the WSe2/MoS2 heterostructure

The researchers say that the valley-polarized holes exhibit near-unity valley polarization and ultralong valley lifetime. The researchers observed a valley-polarized hole population lifetime of more than 1 μs and a valley depolarization lifetime of more than 40 μs at 10 K. The researchers say that near-perfect generation of valley-polarized holes combined with the ultralong valley lifetime may open up new opportunities for novel valleytronics and spintronics applications.

Researchers demonstrate how light can be used to manipulate electron valley

Researchers from the City College of New York have demonstrated how to manipulate the electron valley property in 2D semiconductors. This could be seen as a step towards the realization of valleytronics-based logic gates.

Valley control in 2D semiconductors (CCNY)

To control the valley, the researchers used a light trapping structure called a microcavity. The microcavity gives rise to half-light-half matter quasi-particles which have the fingerprint of the valley property. A laser can be used to optically control the quasi-particles in order to access the electrons occupying specific valley.