Among its characteristics are Cooper pairs with nonzero total momentum and a spatially non-uniform order parameter, leading to normally conducting areas in the system.
Two independent publications in 1964, one by Peter Fulde and Richard A. Ferrell[2] and the other by Anatoly Larkin and Yuri Ovchinnikov,[3][4] theoretically predicted a new state appearing in a certain regime of superconductors at low temperatures and in high magnetic fields.
Good evidence for the existence of the FFLO state was found in organic superconductors using nuclear magnetic resonance (NMR) [7][8][9] and studies of heat capacity.
[19] Most organic superconductors are strongly anisotropic, in particular there are charge-transfer salts based on the molecule BEDT-TTF (or ET, "bisethylendithiotetrathiofulvalene") or BEDT-TSF (or BETS, "bisethylendithiotetraselenafulvalene") that are highly two-dimensional.
When applying large magnetic fields exactly parallel to the conducting planes, penetration depth[20][21][22] demonstrates and specific heat confirms[23][citation needed] the existence of the FFLO state.