Probing the magnetic dichroisms of emergent interfacial magnetic order in rare-earth nickelate / titanate superlattices

Our recent investigation of LaNiO3/LaTiO3 superlattices using resonant inelastic x-ray scat-tering (RIXS) and muon spin rotation (uSR) has revealed the emergence of a novel quasi-2D magnetic order at the superlattice interface. However, the microscopic details of this magnetic order, such as its type (ferromagnetic or antiferromagnetic) and orientation (in-plane or out-of-plane) are still unknown. Its magnetic transition temperature of 18 K measured by uSR is also very low compared to its high magnon energy of ~100 meV measured by RIXS (corresponding to a theoretical transition temperature of >1000 K). Here, we propose to do a systematic study of these LaNiO3/ LaTiO3 superlattices using x-ray magnetic linear and circular dichroism spectrosco-pies (XMLD and XMCD) to determine the type and orientation of its interfacial magnetic order, verify its magnetic transition temperature, and determine its magnetic (quadrupole) moment via the XMCD (XMLD) sum rule. The results will reveal the microscopic details of this interfacial mag-netic order for its potential applications in spintronic and superconductivity research.