Evolution of nematic order through the pseudogap phase in stripe-ordered cuprate superconductors

Electronic nematic order – evidenced by the breaking of rotational symmetry of the electronic structure – has now been reported in several cuprate superconductors. Resonant x-ray scattering (RXS) measurements in the low temperature tetragonal (LTT) structural phase of Nd-doped (La, Sr)₂CuO₄ has established a correlation between the pseudogap phase of the cuprates and the observation of nematicity in overdoped samples, with nematicity vanishing above the pseudogap onset temperature T^∗ and doping p^∗. Here we employ RXS measurements over a wider range of Sr doping, covering more heavily underdoped samples in related materials, (La, Ba)₂CuO₄ and Eu-doped (La, Sr)₂CuO₄. Notably, Eu-doped (La, Sr)₂CuO₄ has a larger LTT transition temperature than Nd-LSCO, but otherwise similar structure and electronic structure. In overdoped samples, these measurements confirm the previous findings in Nd-LSCO, showing evidence for nematic order to vanish above T^∗ and p^∗, as well as a crossover in the structural phase transition from 1st order to 2nd order. We also confirm a cooperative coupling between the Q_x = Q_y = 0 electronic nematic order and CDW order, which breaks both rotational and translational symmetry. In contrast to overdoped samples, in heavily underdoped samples deep within the pseudogap phase, we observe a temperature-independent nematic susceptibility, which is interpreted as a regime of strong and saturated nematic order. These results are discussed in the context of Ginzburg-Landau theory to provide insights into the doping dependence of electronic and structural symmetry breaking.



This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada First Research Excellence Fund, the Canada Foundation for Innovation, the National Research Council Canada, the Canadian Institutes of Health Research, the Government of Saskatchewan, the University of Saskatchewan and CIFAR.