Nanoscale suppression of magnetization at atomically assembled manganite interfaces: XMCD and XRMS measurements

Using circularly polarized x rays, we compare the electronic and magnetic properties of a La_2∕3Sr_1∕3MnO₃(LSMO)∕SrTiO₃(STO) and a modified LSMO∕LaMnO₃(LMO)∕STO interface. Using the technique of x-ray resonant magnetic scattering, we can probe the interfaces of complicated layered structures and quantitatively model depth-dependent magnetic profiles as a function of distance from the interface. Comparisons of the average electronic and magnetic properties at the interface are made independently using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD). The XAS and the XMCD demonstrate that the electronic and magnetic structure of the LMO layer at the modified interface is qualitatively equivalent to the underlying LSMO film. From the temperature dependence of the XMCD, it is found that the near-surface magnetization for both interfaces falls off faster than the bulk magnetization. For all temperatures in the range of 50–300 K, the magnetic profiles for both systems always show a ferromagnetic component at the interface with a significantly suppressed magnetization that evolves to the bulk value over a length scale of ∼1.6–2.4 nm. The LSMO/LMO/STO interface shows a larger ferromagnetic moment than the LSMO/STO interface; however, the difference is only substantial at low temperature.