Kohn–Luttinger superconductivity is a theoretical mechanism for unconventional superconductivity proposed by Walter Kohn and Joaquin Mazdak Luttinger based on Friedel oscillations. In contrast to BCS theory, in which Cooper pairs are formed due to electron–phonon interaction, Kohn–Luttinger mechanism is based on fact that screened Coulomb interaction oscillates as cos ⁡ ⁡ ( 2 k F r + ϕ ϕ ) / r 3 and can create Cooper instability for non-zero angular momentum ℓ ℓ .