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Condensed Matter & Materials Physics

BCS Theory

The microscopic quantum theory of superconductivity developed by Bardeen, Cooper, and Schrieffer in 1957.

Governing formula 2 Δ(0) ≈ 3.52 k_B T_c, E_gap = 2 Δ
SI unit K (Critical Temperature T_c)

In depth

BCS theory demonstrates that attractive lattice phonon interactions overcome Coulomb repulsion between electrons at low temperatures, binding electrons of opposite momentum and spin into Bosonic 'Cooper pairs'. Cooper pairs collapse into a single macroscopic quantum ground state.

Examples in the real world

Explaining the isotope effect and predicting the superconducting energy gap 2Δ in elemental superconductors like lead and tin.