Figure 5. Fermi-surface reconstruction and charge order.

Hall coefficient R_H(T) of YBCO as a function of temperature at a doping p=0.12 (T_c=66 K), for a field H=15 T (red line, from ref. 26). T_max is the temperature at which the Hall coefficient R_H(T) peaks, before it falls to reach negative values—a signature of Fermi-surface reconstruction18,21. T_H is the inflexion point where the downturn in R_H(T) begins. The evolution of R_H(T) is compared with the growth of charge-density-wave modulations in YBCO detected by X-ray diffraction, at the same doping and field24. As seen, the onset of the modulations, at T_CO~130 K, coincides with T_H. This suggests a causal connection between charge order and Fermi-surface reconstruction.