Fig. 4

Domain imaging across the magneto-structural phase transition of Fe_1.08Te. a Constant-current STM image of Fe_1.08Te taken while decreasing the temperature with a rate of 0.1 K min⁻¹ across the magneto-structural phase transition (V_s = 300 mV, I_t = 40 pA, scale bar width 400 nm, color scale from 0 (black) to 3 nm (white), temperature scale from 65.4 K (red) to 64.3 K (blue)). The image is scanned from bottom to top, line by line in the horizontal direction, resulting in a linearly decreasing temperature as given by the temperature scale on the left. Each of the 256 lines takes a time of ≈2.66 s. The phase transition from the \({\cal T}\) (bottom) to the \({\cal M}\) (top) phase occurs at T = 64.4 K. b Same as a, but during increasing the temperature across the magneto-structural phase transition from the top to the bottom of the image (temperature scale from 66.6 K (blue) to 67.2 K (red)). The scanned area is the same as in a as indicated by the defects used as a marker (see ellipses in a, b). The phase transition from \({\cal M}\) (top) to \({\cal T}\) (bottom) phase occurs at T = 67.0 K. c, d Height profiles in the \({\cal M}\) (blue) and \({\cal T}\) (red, black) phases for the cooling (c) and the heating (d) cycles, taken along the dashed lines marked with the corresponding color in a, b, respectively. Note that these profiles were taken from backward scans, i.e., from right to left. e, f Constant-current STM images of the identical surface area in the \({\cal M}\) phase of Fe_1.08Te, containing a step edge (V_s = 300 mV, I_t = 40 pA, scale bar width 300 nm, color scale from 0 (black) to 1.25 nm (white)). In between the images, the sample was heated into the \({\cal T}\) phase and cooled back into the \({\cal M}\) phase