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06-2022

Alignment of Quantified Levels in Valleytronic Materials

वैलीट्रॉनिक सामग्री में परिमाणित स्तरों का संरेखण2):doped monolayer WSe2 Schematic showing Landau’s level in response to an external magnetic field, B. The valleys are shown in blue and orange. The g-factor, g*vK, is enhanced due to dynamic many-body interactions resulting from the change in carrier density in each valley, as the energy difference between the valley extrema, Ez, changes with B. credits: npj computational material (2021). DOI: 10.1038/s41524-021-00665-8″ width=”800″ height=”424″/>

Landau level in doped monolayer tungsten diselenide (WSe.)2): doped monolayer WSe . Schematic showing Landau levels in2, in response to an external magnetic field, B. The valleys are shown in blue and orange. The G-factor, G*Vk, is enhanced due to dynamic many-body interactions arising from the change in carrier density in each valley, as the energy difference between the valley extrema, Ez, changes with b. credits: NPJ Computational Materials (2021). DOI: 10.1038/s41524-021-00665-8

Researchers from the National University of Singapore have predicted that the Landau strata belonging to different basins in a two-dimensional (2D) valleytronic material, monolayer tungsten diselenide (WSe).2), can be aligned in a critical magnetic field.

The alignment of individual 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 quantum electronic levels may enable the creation of particles called pseudo-spinners that are useful for quantum computing applications.

Quantified electronic levels emerge when a magnetic field is applied to a 2D material. These levels are called Landau levels. Of particular interest are the levels of the Landau in the valley material. Valleytronic materials are materials in which one can control not only the charge or spin of an electron, but also the “valley” to which the electron belongs. In general, charge carriers in different valleys travel in opposite directions.

In this work, the research team led by Associate Professor Kwek Su Ying of the Department of Physics of the National University of Singapore developed an approach to account for the effect of dynamic electron–electron interactions when predicting energy levels in valetronic materials in the presence of energy levels. a magnetic field. Their predictions showed that these many-body interactions amplify the effects of magnetic fields on materials by causing changes in their energy levels. When applied to monolayer WSe2, the computational results were found to be in quantitative agreement with the experimental literature, validating the new approach. This amplification is determined by the increase of so-called Lande G-factors.

The team observed that in response to changes in the magnetic field, a change in the population of charge carriers in each valley led to an increase in g-factors. However, when the magnetic field is strong enough such that all carriers are located in the same valley (all carriers move to the blue valley in the image above), this change in carrier population can no longer occur, and g Factors fall suddenly. In this critical magnetic field, charge carriers can oscillate back and forth between the two valleys and this can lead to an alignment of the Landau levels in the two valleys.

Dr. Xuan Fengyuan, a postdoctoral fellow in the research team, said, “Due to the large G-factors present in the WSE2The estimated critical magnetic fields are small so this effect can be felt in standard laboratories.”

“Compared to previous proposals, the alignment of Landau levels predicted in this work is stronger for carrier density fluctuations. Recent observations of partial quantum Hall states in 2D WSe2 suggest the possibility of using Landau level alignment as a means of enabling topological quantum computing applications,” said Prof.


Prediction of magnetic field response in 2-D Valleytronics materials


more information:
Fengyuan Xuan et al, Valley-filling instability and critical magnetic fields for interaction-enhanced Zeeman response in doped WSe2 monolayers, NPJ Computational Materials (2021). DOI: 10.1038/s41524-021-00665-8

Provided by National University of Singapore

Citation: Alignment of Quantitative Levels in Valleytronic Materials (2022, June 14) Retrieved on June 14, 2022 from https://phys.org/news/2022-06-alignment-quantized-valleytronic-materials.html.

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