Buried Interface Magnetism and Near Edge X-ray Absorption Fine Structures Probed by Synchrotron X-ray STM

Synchrotron X-ray STM (SXSTM) combines two of the most powerful materials characterization techniques, synchrotron X-ray and STM. SXSTM has a great potential revolutionize material characterizations with simultaneous elemental, magnetic and topological contrast down to the atomic scale. Here, we present our recent SXSTM results of nanoscale materials measured at the APS of Argonne National Lab. Based on SXSTM X-ray absorption spectroscopy, by employing circular polarized X-rays, we are able to demonstrate X-ray magnetic circular dichroism of LSMO/LNO superlattices at low temperature. Polarization dependent x-ray absorption spectra have been obtained through a specially fabricated tip that captures photo-electrons. Unlike conventional spin-polarized STM, x-ray excitations provide magnetic contrast even with a non-magnetic tip. Here we demonstrate the buried magnetism at LNO/LSMO interface by analyzing the XMCD and near edge X-ray absorption fine structure. Without magnetic field, the magnetism is completely induced by the LNO/LSMO interface through charge transfer and interfacial strain. In contrast, LSMO/LNO superlattice does not present interfacial magnetism. In addition to presenting the recent results, we will also discuss potential future research directions using SXSTM.