Δ(r) = Δ₀cos(Q·r) — spatially modulated Cooper pairing with finite momentum q
The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO/LOFF) state pairs electrons with finite total momentum q ≈ 2h/v_F under a Zeeman field h. The order parameter Δ(r) = Δ₀cos(Q·r) oscillates in space — nodes are normal-metal regions. Pair density waves (PDW) in cuprates are related but intrinsic; they generate secondary CDW and CDW via Δ*∂_x Δ intertwining.