Fig. 3

Magnetic vortex mapping on RbFe₂As₂. a Zero-bias conductance (ZBC) mapping on type A surface under B = 0.5 T (size: 150 × 150 nm²; V_b = 1.2 mV, I = 150 pA, ΔV = 50 μV; scale bar: 30 nm). A spatially averaged core is shown in panel c. Inset is an FFT image aligned to the ZBC map. b Evolution of the dI/dV spectra taken across the vortex core (V_b = 1.5 mV, I = 100 pA, ΔV = 50 μV), along the red arrow in a. A zero-bias peak is observed at the center and splits when leaving the core. c ZBC line profiles along the long and short axes of an averaged vortex core (inset image, scale bar: 20 nm). Solid curves are exponential fits, which yield the coherence lengths ξ^L and ξ^S. d ZBC mapping of type B surface under B = 0.5 T (size: 225 × 225 nm²; V_b = 1.5 mV, I = 120 pA, ΔV = 50 μV; scale bar: 50 nm). The elongated direction of the vortex cores is where the QPI shows arc-like features (inset). e dI/dV spectra taken across the vortex core (V_b = 1.5 mV, I = 100pA, ΔV = 50μV), along the red arrow in d. A zero-bias peak is also observed. f ZBC line profiles along the long and short axes of a vortex core on type B surface (inset image, scale bar: 20 nm) and their exponential fits. The difference between ξ^L and ξ^S on type B surface is more significant than on type A surface. (All the data shown in this figure are taken at T = 20 mK (T_eff = 310 mK))