fig4
Figure 4. The visualization of the anisotropic Ir-O-Ir lattices at negative biases. (A) The STM image of the Na2IrO3 surface taken with an O-decorated tip. The regions highlighted by yellow curves exhibit the zigzag pattern (Vb = -1.6 V, It = 20 pA, image size: 20 × 20 nm2). (B) Highly resolved STM image zoomed from the region marked with a red rectangle in (A). The superimposed Na, O and Ir atoms are represented with blue, red and pink balls, respectively. Ir atoms show differences in contrast, which we label as IrA and IrB, respectively. (C) Height profiles of the IrA-O-IrB bonds along the nearest-neighbor directions of X, Y and Z.
