Current Affair 1:

News:

 

Scientists have discovered superconductivity in twisted bilayer tungsten diselenide (tWSe₂), a new moiré material made from semiconductors, marking a significant advancement in quantum materials research.

What is moiré pattern?

A moiré pattern is an interference pattern that emerges when two periodic structures, such as grids, lattices, or layers of materials, are overlaid with a slight misalignment or rotation. These patterns appear as larger, slower-varying periodic structures, distinct from the original finer patterns.

How It Forms?

1. Imagine two layers with repeating, lattice-like arrangements.
2. If these layers are stacked on top of each other but are slightly rotated or have different periodic spacings, their patterns interfere.
3. This interference creates a new, large-scale pattern—a moiré pattern—that depends on the degree of mismatch (rotation angle or spacing difference).

[Here is an image of a moiré pattern, illustrating the interference created by overlapping two grids with a slight rotation. It demonstrates the wavy, large-scale structures formed due to the alignment mismatch.]

The discovery of superconductivity in twisted bilayer tungsten diselenide (tWSe₂) represents a major milestone in quantum materials research, particularly in the field of moiré materials.

What is tWSe₂?

1. Tungsten diselenide (WSe₂) is a transition metal dichalcogenide (TMD), a type of material with unique electronic properties.
2. In twisted bilayer tungsten diselenide, two layers of WSe₂ are stacked on top of each other with a slight rotational misalignment. This creates a moiré pattern—an interference pattern resulting from the periodic mismatch between the layers.
3. This moiré pattern drastically alters the material's electronic structure, creating new quantum phenomena.

Superconductivity in tWSe₂

Superconductivity is the phenomenon where a material conducts electricity with zero resistance below a certain temperature. When discovered in unconventional systems like tWSe₂, it suggests novel mechanisms at play. In tWSe₂:

1. Twisting the bilayers creates a lattice of “moiré superlattices,” which trap electrons in a highly tunable environment.
2. At specific twist angles (often near the so-called “magic angle”), the electronic interactions can lead to strong correlations, allowing for superconductivity to emerge.

Why is this important?

Expands the toolkit for studying superconductivity:

Most moiré superconductivity studies have focused on graphene-based systems (e.g., twisted bilayer graphene, discovered in 2018). The discovery in a semiconductor like WSe₂ broadens the range of materials with tunable quantum properties.

Novel quantum phases:

tWSe₂ offers unique properties, including strong spin-orbit coupling and valley degrees of freedom, which are absent in graphene systems. This could lead to new types of superconductivity and other quantum phases.

Potential for practical applications:

These discoveries could pave the way for new quantum technologies, such as fault-tolerant quantum computers or ultra-efficient energy transmission.

<< Previous Next >>