Figure 4. H–T phase diagram of FeSe for H||c.

Solid line is the irreversibility line H_irr(T) (ref. ¹⁴). The colour represents the magnitude of Δχ (in 10⁻⁵, scale shown in the colour bar) from magnetic torque measurements (Fig. 2c). Preformed pair regime is determined by the minimum of dρ_xx(H)/dT (blue circles), the peak of Nernst coefficient ν_peak (green circles) and the onset of Δ(1/T₁T) in the NMR measurements (red circles).