Coupled Cu and Mn charge and orbital orders in YBa 2 Cu 3 O 7 /Nd 0.65 (Ca 1-y Sr y ) 0.35 MnO 3 multilayers

The observation of a charge density wave in the underdoped cuprate high Tc superconductors (Cu-CDW) raised a debate about its relationship with superconductivity. In bulk YBa2Cu3O7−δ the Cu-CDW is incipient and mainly pinned by defects. Nevertheless, a large magnetic field can induce a true long-range Cu-CDW order as it suppresses superconductivity. An enhanced Cu-CDW order was also observed in YBa2Cu3O7/La2/3Ca1/3MnO3 multilayers. Here, we show that the magnitude of the Cu-CDW in YBa2Cu3O7−δ / Nd0.65(Ca1-ySry)0.35MnO3 multilayers can be varied by adjusting the strength of the manganite charge and orbital order via the Sr content (tolerance factor). Furthermore, we resolve the reconstruction of the crystal field levels of the interfacial Cu ions that are also affected by the manganite charge and orbital order. This tuneable interfacial coupling and Cu-CDW in YBa2Cu3O7−δ can be used for studying the relationship between the Cu-CDW and superconductivity and, possibly, for inducing new intertwined quantum states.