1 1 9 I H I G H L I G H T S 2 0 2 1
Fig. 99: a) ρ(T) of two devices, oriented along the
a- and b- axis directions, patterned on a 50-nm-
thick underdoped film. TL is the temperature where ρ deviates by 1% from the
linear fit (dashed line). b) Same as panel (a), but on a 10-nm-thick
underdoped film. c-d) H-scans determined by RIXS for both samples,
respectively along the a- and the b- axis
Fig. 100: Left: The copper-oxide planes of YBCO are presented in the strange metal phase, where the strong interaction between electrons, the quantum entanglement , is illustrated in terms of lightning. Right: The same planes are presented when CDW appears. Here, the symmetry of the system is reduced by the appearance of these local modulations of the conducting electrons, which cause the suppression of the strange metal phase. Illustration: Y. Strandqvist.
On the 50-nm-thick films, both the ρ(T) (Figure 99a) and the CDW, detected by RIXS (blue data in Figure 99c-d), are as in detwinned single crystals: on one side, the T-linear resistivity (i.e., the most significant signature of the HTS in the normal state) occurs in a range that is identical along both a- and b-axis directions, and in agreement with the opening of a
pseudogap at the temperature T*; on the other side, the CDW is bidirectional. However, this changed dramatically when the 10-nm-thick films were investigated. Here, the T-linear resistivity was restored almost down to the superconducting critical temperature Tc along one direction (Figure 99b), while the CDW amplitude became unidirectional (green data in Figure 99c-d).