Symbol T_c

Its job in the formula

$T_c$ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Where the article explains it

In the weak-coupling limit, the transition temperature $T_c$ is related to the strength of the electron-phonon coupling N(0)V (density of states at the Fermi level times the pairing interaction) and the characteristic phonon energy $\hbar$$\omega_D$ (the Debye frequency) by: $k_B$ $T_c$ $\approx$ 1.13\, $\hbar$$\omega_D$ \, $e^{-1/N(0)V}$ The exponential is the important feature, not decoration: it says $T_c$ depends on the coupling strength in a way that is extraordinarily sensitive at weak coupling and saturates at strong coupling, and it predicts that heavier isotopes of the same element (which lower $\omega_D$ ) should lower $T_c$ in a specific, measurable way — the isotope effect, observed before BCS existed and one of the clues that pointed toward a phonon mechanism in the first place.

Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →