Valleytronics.com: the valleytronics experts

Researchers from the University at Buffalo discovered a new way to split the energy levels between the valleys in a two-dimensional semiconductor. The researchers used a ferromagnetic compound to pull the valleys apart and keep them at different energy levels - which enables an increase in the separation of the energy in the valley by a factor of 10 compared to an external magnetic field.

The whole device is a two-layered hterostructure made from a 10-nm thick film of europoium sulfide (EuS) which is magnetic and a single layer (<1nm) layer of tungsten diselenide (WSe2) on top. The magnetic field of the bottom layer forced the energy separation of the valleys in the WSe2.

Researchers from the Institute for Basic Science (IBS) in Korea published a new paper that models the behavior of polaritons in microcavities, nanostructures made of a semiconductor material sandwiched between special mirrors (Bragg mirrors).

The new research helps to understand polaritons, microcavities and have potential implications for future valleytronics devices - such taht use valleys of polaritons. The IBS researchers have generated a theoretical model for valley polarization.

Researchers from Princeton University and the University of Texas-Austin have demonstrated that electrons on a crystal bismuth exhibit the Nematic Quantum Hall Liquid effect at very low temperatures.

This is the first time that a quantum fluid of electrons is visualized. As valleytronics aims to exploit the energy level of electrons in relation to their momentum, this is an important step toward realizing this technology.

Researchers from Penn State University demonstrated a new device, based on bi-layer graphene, that provides an experimental proof of the ability to control electron-flow by the valley degree of freedom. This is still an early-stage development, but could be seen as an important step towards valleytronics.

The device is built from a bi-layer graphene, and gates above and below the graphene layer. Adding an electric field perpendicular to the plane opens a bandgap in the bi-layer graphene, and a physical gap (70 nanometer in height) is left, in which one-dimensional metallic states (wires) exists. These states act as valleytronics valves.

Researchers at the University of Geneva proposed a novel approach to optically ‘pump’ carriers valley-selectively using a high-purity bismuth crystal.

In bismuth there are three valleys and the electrons orbit in magnetic field that are strongly elongated along one direction due the interaction with the atomic lattice. Each valley has its own direction - which means that the direction can be used to discriminate between the valleys.

Researchers at Berkeley Lab have experimentally demonstrated the ability to electrically generate and control valley electrons in transition metal dichalcogenide (TMDC, a 2D semiconductor) .

The researchers say that this is the first demonstration of electrical excitation and control of valley electrons. TDMCs are considered to be more mature (closer to production) than any other semiconductors that exhibit valleytronic properties.

We are proud to be writing the first in what we hope will become a long line of Valleytronics.com posts.

This site was established in order to provide a deeper understanding and up-to-date knowledge in the field of valleytronics research and commercialization.