Fig. 2: Crystal structure characterization of 2D Cr8Se12 on graphite.
From: Observation of kagome-like bands in two-dimensional semiconducting Cr8Se12
a STM topography (Vs = 2 V, I = 5 pA) of the chromium selenide sample with an orange dashed line across the 5-atomic-layer Cr2Se3 and 7-atomic-layer Cr8Se12. Inset: STM line profile along the orange dashed line. Scale bar: 15 nm. b LEED pattern of the as-grown chromium selenide sample on graphite. The black, red, and blue circles denote diffraction patterns from the graphite, 2D Cr2Se3, and 2D Cr8Se12, respectively. c, d STM (c) and nc-AFM (d) images of the interface region acquired at the same scanning window. The lattice of 2D Cr8Se12 (2D Cr2Se3) is represented by the blue (red) circles. The primitive lattice vectors of 2D Cr8Se12 (2D Cr2Se3) are denoted by a and b (a0 and b0), respectively. Imaging conditions for Fig. 2c: Vs = 1.6 V, I = 100 pA. Imaging conditions for the lower (upper) part of Fig. 2d: z0 = −200 pm (z1 = −470 pm = z0 −270 pm) relative to Vs = 0.3 V, I = 100 pA. Scale bars: 1.6 nm. e, f Atomic-resolved (e) constant height STM and (f) nc-AFM (Vs = −0.01 V, z = −340 pm relative to Vs = 0.3 V, I = 100 pA) images of 2D Cr8Se12 obtained within the same scanning window, with the unit cell marked by the white rhombus and with different interatomic distances (a1, a1’, and a2) by triangles with diverse colors. Scale bars: 0.6 nm. g Statistical analysis of the measured nearest-neighbor interatomic distances: a1 = 0.370 ± 0.005 nm, a1’ = 0.387 ± 0.007 nm and a2 = 0.355 ± 0.005 nm. The distances were determined from Gaussian curve fitting of the histograms, with errors representing the standard deviations. h Crystal structures of 2D Cr8Se12 along different axes with the unit cell marked.
