Valley Physics of Un-polarized States

Feng-Wu Chen^1*, Mei-Yin Chou^2,3,4, Ching-En Hung¹, Yen-Ju Lin¹, Yu-Shu Wu^1,5

¹Electrical Engineering, National Tsing-Hua University, Hsin-Chu, Taiwan
²Institute of Atomic and Molecular Science, Academia Sinica, Taipei, Taiwan
³Department of Physics, National Taiwan University, Taipei, Taiwan
⁴School of Physics, Georgia Institute of Technology, Atlanta, USA
⁵Physics Department, National Tsing-Hua University, Hsin-Chu, Taiwan

* Presenter:Feng-Wu Chen, email:i7685.ee96@gmail.com

The recent rise of hexagonal two-dimensional (2D) materials has opened up a new field known as valleytronics for device applications, by exploiting an extra degree of freedom (DOF) — valley pseudospin, which originates from two degenerate energy valleys, residing at first Brillouin zone corners. These two valleys are separately addressable, based on the coupling of the valley magnetic moment (VMM) and various external fields. Presently, the VMM–a global physical quantity–has gained much attention for various purposes, regarding physics studies, such as the valley Hall effect, and applications, such as valley filters, valley FETs, and so on. As a critical step forward, in this presentation we will introduce the concept of local valley magnetic moment (LVMM) and its implication for valleytronic applications. For demonstration, we will show how valley-unpolarized states can thus play a critical role in transmission behavior in 2D materials.

Keywords: Valleytronics, Local valley magnetic moment, Quantum transport, Two-dimensional materials