SUPERCONDUCTORS
- SCI & TECH
News:
Superconductivity: Stay
in the flow
What's
in the news?
●
A property in the realm of materials
science that has been the source of endless fascination for scientists is
superconductivity.
Key
takeaways:
●
Materials possess an innate resistance to
the flow of an electric current, which leads to a loss of electrical energy and
heat. Most materials retain this resistance even when cooled to a very low
temperature – but some don’t.
●
These are the superconductors. They can
infinitely conduct a direct current without losing any energy as long as they
stay in the superconducting state. (One of the hallmarks of this state is that
if it is placed in a weak magnetic field, the material won’t allow the field to
enter its body.)
Superconductors:
●
Superconducting materials show zero electrical resistance at low
temperatures, which allows them to conduct 'supercurrents' without
dissipation.
●
A superconductor is a material that
achieves superconductivity, which is a state of matter that has no electrical
resistance and does not allow magnetic fields to penetrate.
●
An electric current in a superconductor
can persist indefinitely.
●
Superconductivity can typically be
achieved at very cold temperatures.
●
Superconductors can be metals, ceramics,
organic materials, or heavily doped semiconductors - Only criteria is that
material should conduct electricity without resistance. Popular superconductors
are Lead and Mercury.
Application:
●
Superconducting electromagnets are also
used in maglev trains, experimental
nuclear fusion reactors and high-energy particle accelerator laboratories.
●
Superconductors are also used to power railguns and coilguns, cell phone
base stations, fast digital circuits and particle detectors.
●
It is also used in quantum computers.
Go
back to basics:
Bardeen-Cooper-Schrieffer
(BCS) Theory:
●
In BCS superconductors, vibrational energy
released by the grid of atoms encourages electrons to pair up, forming
so-called Cooper pairs.
●
These Copper pairs can move like water in
a stream, facing no resistance to their flow, below a threshold temperature.
●
The researchers accounted for the
relationship between an electron’s spin and momentum; they could explain why
mercury has such a low threshold temperature (around –270°C).
●
Coulomb
repulsion:
○
One
electron in each pair in mercury occupied a higher energy level than the other.
This detail reportedly lowered the Coulomb repulsion (like charges repel)
between them and nurtured superconductivity.