Distinct oxygen hole doping in different layers of $ m Sr_{2}CuO_{4-\delta}-La_{2}CuO_4$ superlattices

摘要

X-ray absorption in $\rm Sr_{2}CuO_{4-\delta}-La_{2}CuO_4$ (SCO-LCO)superlattices shows a variable occupation with doping of a hole state differentfrom holes doped for $x \lesssim x_{optimal}$ in bulk $\rm La_{2-x}Sr_{x}CuO_4$and suggests that this hole state is on apical oxygen atoms and polarized inthe $a-b$ plane. Considering the surface reflectivity gives a good qualitativedescription of the line shapes of resonant soft X-ray scattering. Theinterference between superlattice and surface reflections was used todistinguish between scatterers in the SCO and the LCO layers, with the two holestates maximized in different layers of the superlattice.