Extended Data Fig. 4: STM images of the 40-UC FeTe film after four-cycle Te-annealing treatments (that is, cycle IV).
a, STM image (20 × 20 nm2) measured using a lower Vs (Vs = −10 mV and Is = 1 nA). Inset, FT image. b, STM image (20 × 20 nm2) of the same region in a measured using a higher Vs (Vs = 3.5 V and Is = 1 nA). The red spots in b represent the interstitial Fe atoms. Inset, the corresponding overlay of the STM images in a and b. The red (blue) areas in b, inset represent the AFM (non-AFM) region shown in a. The black spots in b, inset represent the interstitial Fe atoms in b. The STM images in a and b are acquired using a spin-polarized tip at T = 4.2 K. Scale bars, 2 nm (a,b); 1 Å−1 (a, inset); 2 nm (b, inset).
