Extended Data Fig. 7: Flux trapping in S2.

We compare the response of the sample on sweeping H_z after field cooling and zero field cooling at T = 81 K. (a) On field cooling at H_z = 103 G we measure a trapped flux. On ramping to large fields in the direction opposite to this trapped flux (H_z = − 154 G), we measure an inversion of the flux trapped field. (b) In contrast, the sample is robust to flux penetration on zero field cooling. Specifically, on ramping the external field to ∣H_z∣ = 154 G in both the positive and negative directions, we continue to observe a local suppression in B_z without any appreciable flux trapping. (c) After zero field cooling, the sample exhibits flux penetration only on ramping the external field to much larger magnitudes (∣H_z∣ ~ 240 G). Here, we measure a response similar to the case of field cooling. Specifically, on ramping to a field H_z = 240 G we find a flux trapped field B_z = 18 G (measured after returning to H_z = 0 G). Similarly, after ramping to a field H_z = − 240 G, the direction of the trapped flux changes (i.e., we measure B_z = − 28 G on returning back to H_z = 0 G). All measurements are performed at the spatial location shown by the inverted white triangle in the fluorescence scan [inset of (a)].