Context: A group of scientists affiliated with research institutes in China and Japan have reported finding a sign of superconductivity in a material that was at the centre of a controversy last year over similar claims. The sign in question is called the Meissner effect. 

About:

Superconductivity is an inherent property found in various materials, including chemical elements (e.g., mercury or lead), alloys (such as niobium-titanium, germanium-niobium, and niobium nitride), ceramics (YBCO and magnesium diboride), and organic superconductors (fullerenes and carbon nanotubes).

Properties of Superconductors:

• Phase Transition (at critical temperature): Superconductivity manifests when the temperature (T) is reduced below a critical temperature (Tc).
• Zero Resistance to Current: Below the critical temperature, superconductors exhibit zero resistance to electric current.
• Meissner Effect: This refers to the expulsion of a magnetic field from a superconductor when cooled below its critical temperature. This property is utilized in the creation of high-speed magnetically-levitated trains (MAGLEV).
• London Moment: A phenomenon where a spinning superconductor generates a magnetic field whose axis aligns precisely with the spin axis.

High-Temperature Superconductors (HTS):

These are materials that display superconducting behavior at unusually high temperatures.