Fig. 2: Bias-dependent STM imaging of NbSe2 at 1.2 K.
From: Multiband charge density wave exposed in a transition metal dichalcogenide
Constant current topography showing the atomic lattice and CDW at aVb = 50 mV, b Vb = − 50 mV and cVb = − 150 mV (Solely for visualization, the STM image in c has been corrected for diagonal running sharp lines (with wavelength much longer than those of the CDW) which arose due to a tiny horizontal tilt of the sample leading to a least significant bit issue in the digital–analogue conversion of the piezo voltage.) with It = 100 pA. d, f and h are magnified images of the areas marked by the red squares in a, b and c, respectively. The overall imaging contrast is very different in these cases, although the atomic lattice appears identical in all images (Supplementary Fig. 1). e, g and i shows the magnified image of the large Fourier-filtered image of the CDWs at the same location as shown in d, f and h, respectively. It demonstrates that the variation of contrast observed in d, f and h is stemming from a variation in the appearance of the CDW at different biases. These appearances can be quantified by a single parameter: the dephasing parameter which describes the relative position of the three CDWs. j–l show the spatial variation of the dephasing parameter determined by fitting the CDW modulations of the STM images shown in a-c, respectively. The red squares correspond to the same area that is highlighted in a–c and magnified in d–i. Scalebars: 10 nm in a–c and j–l; 1 nm in d–i.
