Fig. 7

Higuchi method applied at T=5 K and σ=0 MPa. Total scaled roughness L_k as a function of inverse magnification \(\frac {1}{k}\) (heavy blue line). Two power laws are fitted to the small (orange) and to the large (green) length scales separated by the optimal k_s (marked with a dashed vertical black line). The correlation length ξ is determined from the intersection point of the two power law fits (marked with a dashed vertical red line) and the Hurst exponents H₁ and H₂ from the corresponding slopes. The inset shows the fit score function S(k_s) as a function of \(\frac {1}{k_{\mathrm {s}}}\). The red dot marks the minimum value that yields the optimal k_s