Consider the following statements:

Statement I: Many metals have finite conductivity at room temperature but exhibit infinite conductivity at extremely low temperatures.

Statement II: At very low temperatures, electrons weakly attract each other, forming Cooper pairs, which undergo a phase transition into a superconducting state with infinite conductivity.

Which one of the following is correct in respect of the above statements?

The correct answer is option 1.

In News

• A research team from China and Japan recently reported strong evidence that niobium diselenide (NbSe₂) can exhibit properties of a Bose metal, challenging conventional theories of superconductivity and metallic conductivity at low temperatures.

Key Points

• Many metals exhibit finite conductivity at room temperature but transition to a superconducting state with infinite conductivity when cooled below a critical temperature. Hence, Statement I is correct.
• As metals cool, electrons weakly attract each other, forming Cooper pairs. These pairs undergo a phase transition into a superconducting state, eliminating electrical resistance and leading to infinite conductivity. Hence, Statement II is correct.
• The formation of Cooper pairs and their phase transition into a superconducting state directly result in infinite conductivity at low temperatures. Hence, Statement II correctly explains Statement I.

Additional Information

• Superconductors exhibit zero electrical resistance and expel magnetic fields (Meissner effect).
• Type-II superconductors (like NbSe₂) can maintain superconductivity even in the presence of a magnetic field.
• The Bose metal hypothesis challenges the idea that metals must become either insulators or superconductors at absolute zero, suggesting an intermediate metallic state where Cooper pairs form but do not fully condense.