Extended Data Fig. 7: Structural transition in Nd-LSCO.
a) Structural phase diagram of Nd-LSCO as a function of doping. The black dots and black line mark the structural transition from the LTO1 phase to the LTT phase at low temperature, at TLTT, as measured by x-ray diffraction36. The squares mark TLTT in our samples with p = 0.21 (blue) and p = 0.24 (green), as detected by dilatometry measurements (see panel b). b) Change in sample length L as a function of temperature, plotted as its derivative dL / dT vs T, measured in our c-axis sample of Nd-LSCO with p = 0.21 (blue) and in a sample of Nd-LSCO cut from the same large single crystal as, and next to, our c-axis sample of Nd-LSCO with p = 0.24 (green). The dip in the curves marks the structural phase transition from the LTO1 phase above to the LTT phase below the transition temperature TLTT, where TLTT = 82 ± 5 K at p = 0.21 and TLTT = 45 ± 10 K at p = 0.24. The error bars on the two values of TLTT correspond to the full width of each corresponding dip. These data confirm that our two Nd-LSCO samples, with p = 0.21 and p = 0.24, have the same crystal structure. This shows that all the differences observed in their properties, in particular the dramatic difference in their thermal Hall conductivity κzy (Fig. 1), are not due to a difference in structural properties. Instead, these differences are linked with the onset of the pseudogap phase at p* = 0.23.
