Extended Data Fig. 4: Uniaxial strain of the moiré superlattice.

a, Topography image shown in Fig. 1b. b, the corresponding FFT image. c, d, 1D height modulation along three directions (c; denoted by the red arrows in a), and the corresponding FFT results (d). The different moiré periods along the three different directions yields a uniaxial strain of 0.39% along the pink double-arrowed line (a, b). As a comparison, the stripe direction of the n = 1/2 Wigner crystal state is denoted by the yellow double-arrowed line.