Context: Recently, scientists have discovered that moiré materials made from semiconductor materials can exhibit the phenomenon of superconductivity. This breakthrough opens the door for developing new quantum materials.
Relevance of the Topic: Prelims- Moiré Material, Superconductors (properties and applications)
What are Moiré Materials?
- Moiré materials are created by stacking two layers of a two-dimensional material and then twisting one layer at a small angle.
- The misalignment caused by the small twist produces a completely different pattern known as the moiré pattern. This significantly alters the material's electronic properties and facilitates its unusual applications.
The Recent Breakthrough:
- The researchers explored superconductivity in twisted bilayer tungsten diselenide (tWSe₂). It is a moiré material created by stacking two layers of tungsten diselenide (a semiconductor) and rotating one layer by a small angle. The critical transition temperature for superconductivity in this material was observed at approximately –272.93°C.
- Earlier, the moire material made up from graphene had also displayed superconductivity.
What are Superconductors?
- Superconductors are materials that when cooled to temperatures ranging from near absolute zero (0 degrees Kelvin, -273 degrees Celsius) have zero resistance or do not resist the flow of current. The temperature at which electrical resistance is zero is called the critical temperature (Tc) and this temperature is a characteristic of the material. E.g., Aluminium, Niobium, Magnesium diboride, Yttrium barium copper oxide display superconducting properties.
- However, every superconductor made so far has required extraordinarily high pressures (millions of Pascal), and very low temperatures. E.g., Aluminium becomes superconducting at temperatures lower than (minus) –250° C.
Hence, scientists have been looking for such materials for decades which can remain superconductors at room temperature.
Important properties of Superconductors:
- Electronic effect (Infinite conductivity with Zero resistance): When the temperature of superconductors is reduced below a critical temperature, its resistance suddenly reduces to zero and thus it offers infinite conductivity. E.g., Mercury becomes a superconductor below 4 kelvin.
- Magnetic effect (Complete expulsion of Magnetic field): Superconductors are diamagnetic i.e., they oppose the magnetic field or do not allow the magnetic field lines to penetrate them. (This phenomenon is called the Meissner effect)
- However, there is a certain value of the magnetic field (critical magnetic field) beyond which the superconductors lose superconductivity and convert into conductors.
Significance or utility of Superconductors:
- Elimination of the loss of energyas electricity moves along the wire would mean longer-lasting batteries and more-efficient power grids.
- Need: Presently, a portion of the electricity generated at every power plant is lost during transmission because the wires and cables that carry the current have electrical resistance.
- Potential applications include- Magnetic-energy storage systems, magnetic levitation trains, superconducting magnetic refrigerators, etc.
- Huge potential for revolutionary technologies, including efficient quantum computers, as superconductors can exhibit quantum phenomena.
Challenges in utilising Superconductors:
- Maintaining Low Operating Temperatures: Most superconductors require liquid helium or nitrogen cooling, making them expensive to maintain.
- High Pressure Requirement: Some materials only exhibit superconductivity under millions of Pascals of pressure.
- Scalability: Manufacturing and deploying superconducting materials at an industrial scale remain challenging.