A clear picture of how mercury becomes a superconductor

Subject :Science and Technology

Context:

In 1911, Dutch physicist Heike Kamerlingh Onnes discovered superconductivity in mercury. He found that at a very low temperature, called the threshold temperature, solid mercury offers no resistance to the flow of electric current.

Mercury:

Mercury is a naturally occurring element that is found in air, water and soil.
Released into the atmosphere through natural processes such as weathering of rocks, volcanic eruptions, geothermal activities, forest fires, etc.
Mercury is also released through human activities.
It is the only metal which remains liquid at room temperature.

The BCS Theory:

Scientists later classified mercury as a conventional superconductor because its superconductivity could be explained by the concepts of 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 Cooper pairs can move like water in a stream, facing no resistance to their flow, below a threshold temperature.
However, scientists have never fully understood how it operates in mercury — the oldest superconductor.

What researchers have done now?

The researchers used “state-of-the-art theoretical and computational approaches” and found that “all physical properties relevant for conventional superconductivity are anomalous in some respect” in mercury.
By including certain factors that physicists had previously sidelined, the group’s calculations led to a clearer picture of how superconductivity emerges in mercury.
The group found that 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.
Thus, the group has explained how mercury becomes a superconductor below its threshold temperature.

Superconductors: https://optimizeias.com/superconductors/