Technical / research

Researchers develop a trilayer TMD heterostructure with interlayer excitons

Researchers from China's Tsinghua University developed a novel material, made from a stack of 2D materials, that offers interlayer excitons, useful for valleytronics applications.

The new material is a trilayer TMD heterostructure, composed of molybdenum and sulfur, molybdenum and selenium, and tungsten and selenium. Using photoluminescence spectroscopy, the researchers confirmed the presence of interlayer excitons and described various properties and requirements of the phenomenon.

Read the full story Posted: Jun 29,2022

Researchers developed an approach to align Landau levels of different valleys in 2D materials

Researchers from the National University of Singapore researchers have developed an approach to account for the effect of dynamical electron-electron interactions when predicting the energy levels in valleytronic materials in the presence of a magnetic field.

The researchers predicted that Landau levels belonging to different valleys in a two-dimensional (2D) valleytronic material, monolayer tungsten diselenide (WSe2), can be aligned at a critical magnetic field. The alignment of distinct entities, such as two laser beams, or two pillars, is a common goal in many fields of science and engineering. In the more exotic world of quantum mechanics, the alignment of quantized electronic levels can enable the creation of particles called pseudo-spinors that are useful for quantum computing applications.

Read the full story Posted: Jun 16,2022

IIT Bombay researchers developed a valley polariser based on 2-D Xenes

Researchers from the Indian Institute of Technology Bombay (IIT Bombay) have proposed a device structure for a valley polariser which is robust, all-electrical, and can be seamlessly integrated with modern electronics. The device can be fabricated using existing fabrication techniques.

The device is based on 2D-Xene materials. A single-layer of 2-D Xene is used as the charge carrying channel. A terminal called a gate controls the electric current flowing through the channel, similar to how a gate controls the current in the modern transistor design. The gate structure, which is also used to create the valley separation, sandwiches the 2-D Xene ribbon.

Read the full story Posted: May 19,2022

Researchers show it is possible to realize a valleytronics device in pristine graphene

Researchers from Germany (Max-Born Institute) and India (IIT Bombay) have shown that it is possible to realize a valleytronics device in pristine graphene.

Reading and writing valley-selective electron excitations in graphene (image)

Graphene (and other graphene-like systems) feature an extra degree of electron freedom, or valley pseudo-spin. This has interesting potential in valleytronics applications, but the implementation of valleytronics ideas has been so far limited to gapped graphene-like semiconducting 2D materials, most commonly transition metal dichalcogenides, and has never been attempted in pristine graphene, because graphene monolayers have zero bandgap, zero Berry curvature, and thus nearly identical valleys,.

Read the full story Posted: Jul 19,2021

Researchers demonstrate how few-cycle linearly polarized pulses can induce a high degree of valley polarization

Scientists from several research institutes in Germany and the UK have demonstrated that few-cycle linearly polarized pulses can induce a high degree of valley polarization.

few-cycle linearly polarized pulses can induce a high degree of valley polarization

The mechanism to induce such polarization does not rely on the optical selection rules, and therefore can be in principle used in inversion symmetric materials, such as TMD bilayers or graphene. This could enable the design of ultrafast valleytronic devices.

Read the full story Posted: Feb 26,2021

Researchers have demonstrated electrical valley control in 3D dual-gate diamond field-effect transistors

Researchers from Sweden's Uppsala university and from UK's Element Six have demonstrated electrical valley control in 3D dual-gate diamond field-effect transistors.

Electron density in different valleys after electron injection in a dual-gate valleytronic transistor (Uppsala university)

The team has fabricated valley transistors on single-crystalline diamond plates with ultra-low nitrogen impurity concentrations. A dual-gate configuration was used to gain a high degree of freedom of the control of the valley currents. The control of location and time of the valley-polarized currents was achieved by adding multiple drain electrodes.

Read the full story Posted: Feb 21,2021

A 2D derivative of perovskite could hold the key for future valleytronics devices

Researchers from Rice University and Texas A&M University have discovered that a 2D derivative of perovskite has a good potential for valleytronics applications.

The researchers synthesized a layered compound of cesium, bismuth and iodine that is able to store the valley states of electrons, but only in the structure's odd layers. These bits can be set with polarized light, and the even layers appear to protect the odd ones from the kind of field interference that bedevils other perovskites, according to the researchers.

Read the full story Posted: Oct 27,2020