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  Hameed, S.; Liu, Y.; Rabinovich, K. S.; Kim, G.; Neumann, M.; Wochner, P.; Christiani, G.; Logvenov, G.; Higuchi, K.; Brookes, N. B.; Weschke, E.; Yakhou-Harris, F.; Boris, A. V.; Keimer, B.; Minola, M.: Interplay between electronic and atomic short-range order in La_2-xCa_xCuO_4-δ: Temperature and doping dependence. Physical Review B 112 (2025), p. L161114/1-8

10.1103/kyhl-lsw2
Open Access Version

Abstract:
Complex oxides are well-known to develop oxygen ordering patterns with well-defined periodicities, but their interplay with the electronic structure remains largely unexplored. Here, we report resonant and nonresonant x-ray diffraction data indicating a four-unit-cell periodic superstructure related to oxygen vacancy ordering in La2−𝑥⁢Ca𝑥⁢CuO4−𝛿 films with Ca dopant concentrations from the underdoped (𝑥=0.15) to the extremely overdoped (𝑥=0.50) regime. Whereas the oxygen superstructure is temperature independent up to 300 K, a strongly temperature-dependent electronic charge density wave (CDW) is observed in the underdoped and slightly overdoped regimes (𝑥≤0.20). The periodicity, in-plane, and out-of-plane correlation lengths of the CDW are locked in by the oxygen superstructure. Our results highlight the interdependence of electronic and atomic ordering phenomena and underscore the necessity of determining the temperature dependence to distinguish electronic and lattice atomic contributions to superstructures.