Figure 6: STM topography of FeSe/SrTiO 3 films before and after being annealed under different conditions. | Nature Communications

Figure 6: STM topography of FeSe/SrTiO 3 films before and after being annealed under different conditions.

From: Dichotomy of the electronic structure and superconductivity between single-layer and double-layer FeSe/SrTiO3 films

Figure 6

(a) STM image of an as-grown single-layer-dominant FeSe/SrTiO3 film. (b) STM image after the sample was annealed at 450 °C for 15 h. The grey areas represent single layer (1UC) while the bright areas represent double layer (2UC), as marked by arrows. (c) STM image of an as-grown double-layer-dominant FeSe/SrTiO3 film. (d) Its corresponding STM image after being annealed at 500 °C for 3 h. In this case, the dark region represents the single-layer area (1UC), grey regions represent the double-layer area (2UC) and the bright region represents the triple-layer area, as marked by arrows. Before annealing, double-layer regions dominate with a small amount of triple-layer regions. After annealing at 500 °C for 3 h, the area of the initial triple-layer regions is reduced, and single-layer regions emerge that are absent in the original sample before annealing. Note that, in both samples, the field of view taken before and after the annealing are not exactly on the same area.

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