New Moiré Superconductor

Syllabus: GS3/ S&T

In News

• Recent breakthroughs show that semiconductor-based moiré materials, like twisted bilayer tungsten diselenide (tWSe₂), exhibit superconductivity.

Moiré Patterns and Their Impact

• Formation: A moiré pattern arises when two identical layers of material are stacked and twisted at a small angle.
• Flat Bands: The twist causes the electronic energy bands to flatten, reducing the variation in energy among electrons. This flatness:
  • Slows electron movement, making them “heavy.”
  • Encourages strong electron-electron interactions, essential for superconductivity.

Superconductivity in Semiconductor Moiré Materials

• tWSe₂ Superconductivity: Researchers studied twisted bilayer tungsten diselenide with a 3.65° twist.
  • Superconductivity emerged when the electronic states were half-filled, with a critical temperature of approximately –272.93°C.
  • The material showed stability and coherence, making its superconducting state robust and less fragile compared to graphene-based systems.
• Mechanism: In tWSe₂, superconductivity stems from electron-electron interactions and the half-band filling, contrasting with graphene, where electron-lattice interactions dominate.
• Transition to Insulating State: By altering the material’s electronic configuration, tWSe₂ could transition between superconducting and insulating states, revealing its tunability.

Advantages of Semiconductor Moiré Systems

• Stability: The study on twisted bilayer tungsten diselenide (tWSe₂) demonstrates stable superconductivity in semiconductors, marking a significant leap in quantum materials research.
• Coherence Length: The material’s coherence length (distance over which superconductivity persists) is 10 times longer than in other moiré materials, making it more robust.
• Exploratory Potential: Open doors to designing new quantum materials with tunable electronic and superconducting properties.

Source: TH