Fig. 2: Lattice and CDW probed by XRD under uniaxial stresses.
a 0 16 0, 1 15 0, and 0 16 1 Bragg peak intensities normalized to 1, plotted along the longitudinal 2θ direction, for 3 sets of forces: without applied force (gray curves), with Fa = 1.62 kg (red curves) and Fc = 1.64 kg (blue curves). Each Bragg reflection displays the \({K}_{{\alpha }_{1}}\) and \({K}_{{\alpha }_{2}}\) components of the x-ray source. b Evolution of the in-plane and out-of-plane lattice constants of TbTe3, obtained from the fit of the 3 non-colinear Bragg peaks shown in a as a function of Fa and −Fc. Δa/a ~ −Δc/c ~ 0.3% and Δb/b ~ −0.03% at maximum deformation, which corresponds to an in-plane (resp. out-of-plane) Poisson ratio νac ~ 1 (resp. νab = νcb ~ 0.1). c Evolution of the a/c ratio as a function of the same forces, at several temperatures between 200 K and 310 K. The gray line is obtained by a linear fit of all data points: a/c = αF + β, with F = Fa for F > 0 and F = − Fc for F < 0, α = 0.0032 kg−1 and \(\beta={\left(a/c\right)}_{F=0} \sim 0.9982\pm 0.001\) which is consistent with the expected a/c ratio in the pristine state. a/c = 1 is obtained for Fa ~ 0.6 ± 0.1 kg. The error bars on the lattice constants in b and c are given by the standard deviation obtained after fitting the Bragg peaks shown a (see Supplementary Equation 5). The error bar on the applied force is ± 0.1 kg. d Rocking scans on the 1 15 2/7, 1 15 −2/7 peaks associated to the CDW along c and 2/7 15 1 peak associated to the CDW along a, as a function of a/c ratio, at T = 250 K. The a/c ratio was computed from the uniaxial forces Fa and Fc using the linear fit shown in c. The rocking angle ω is taken relative to the peak position in the pristine state.
