Fig. 2: PDW state in 2H-NbSe2.
From: Directly visualizing nematic superconductivity driven by the pair density wave in NbSe2
a A small-scale topography T(r) of AC-CDW order. Scale bar: 1 nm. b,c The waterfall plot of dI/dV(V) tunneling spectra taken along the orange arrow marked in (a). Black dashed lines are guides to the eye to follow the modulation of coherence peaks. d 1D gap map Δ(r) (orange curve) extracted from (b) and (c). The T(r) (turquoise curve) presents the modulation of topography at AC-CDW region. The black curve is fitted by using the formula Δ(r) = Δ0 + Δpcos(Q1 ∙ r), where Δ0 = 1.361 meV, Δp = 0.017 meV, |Q1 | = 2π/3a0. The Δ(r) is in-phase with CDW order (black dashed lines). e H(r) (purple curve) extracted from (b) and (c). The T(r) (turquoise curve) presents the modulation of topography at AC-CDW region. The phase difference between the H(r) and CDW order is about 2π/3, as indicated by the black dashed lines. f Fourier transforms (FT) of Δ(r), H(r) and T(r) in (d) and (e), labeled as Δ(q), H(q) and T(q), respectively. It shows that Δ(r) and H(r) have the same period of T(r) (black dashed line). Offsets are set to orange and purple curves for clarity. Experimental setpoints in (a–c): Vs = −4 mV, It = 400 pA.
